Oily grinding fluid for precise grinding of LED wafer

Abstract

The invention discloses an oily grinding fluid for precise grinding of LED wafers, which is prepared from the following raw materials in percentage by mass: 8-15% of a lubricant, 0.5-5% of a wetting dispersant, 0.5-5% of an anti-wear agent, 0.5-5% of fatty amine polyoxyethylene ether sodium sulfate, 0.5-6% of a suspending agent, 0.5-3% of diamond micro-powder and the balance of matrix oil, with the sum of the mass percentages being 100%. When the oily grinding fluid is applied to precise grinding and precise machining of LED wafers, the oily grinding fluid has the outstanding characteristics of high grinding rate, controllable disc temperature of a grinding disc and small TTV, the grinding machining efficiency can be improved, the machining cost can be reduced, and the oily grinding fluid is small in smell, easy to clean and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of polishing slurry preparation technology, specifically relating to an oil-based polishing slurry for precision polishing of LED wafers. Background Technology

[0002] Currently, commercially available polishing slurries are divided into two types: water-based and oil-based. Compared to water-based slurries, which have drawbacks in actual production such as low polishing speed, easy scratching, and tendency for diamond abrasive particles to aggregate during polishing, resulting in shorter abrasive lifespan and higher workpiece surface roughness, oil-based slurries not only have a polishing and removing effect but also lubrication and rust prevention properties. Therefore, oil-based slurries are more widely used. Traditional oil-based slurries are prone to uneven abrasive dispersion and poor suspension during polishing, leading to rapid settling and abrasive particle aggregation. Under high pressure, the heat generated by continuous mechanical polishing friction cannot be dissipated in time, causing the polishing disc temperature to rise rapidly with polishing time. This temperature change affects the polishing speed, leading to instability and potentially incomplete or excessive polishing of LED wafers. Therefore, solving the problems of poor dispersion, low polishing speed, and excessively high polishing disc temperature during polishing has become a pressing technical bottleneck. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides an oil-based polishing slurry for precision polishing of LED wafers. This composition has the advantages of good dispersibility, high polishing rate, controllable polishing disc temperature, and low TTV, which can effectively improve processing speed and reduce processing costs.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A cleaning composition for precision grinding of LED wafers, comprising, by weight percentage (100%), the following raw materials in the following weight percentages: 8-15% lubricant, 0.5-5% wetting and dispersing agent, 0.5-5% anti-wear agent, 0.5-5% sodium fatty amine polyoxyethylene ether sulfate, 0.5-6% suspending agent, 0.5-3% diamond micron powder, with the balance being base oil. The general structural formula of the sodium fatty amine polyoxyethylene ether sulfate is as follows: , where n = 1 to 5.

[0005] Furthermore, the lubricant is one or more of butyl stearate, isopropyl palmitate, glyceryl tristearate, and triethanolamine oleate soap.

[0006] Furthermore, the wetting and dispersing agent is one or more of sodium alkylbenzene sulfonate, polymethacrylate, monoalkyl phosphate, and polyoxyethylene ether phosphate.

[0007] Furthermore, the anti-wear agent is one or more of p-phenylenediamine, ethylenediamine, diethanolamine, triethanolamine, and aniline.

[0008] Furthermore, the suspending agent is any one or more of organobentonite, polyacrylamide, sodium carboxymethyl cellulose, and sodium metasilicate.

[0009] Furthermore, the particle size of the diamond powder is controlled between 0.3-3 μm.

[0010] Furthermore, the base oil includes white oil and solvent oil, wherein the solvent oil is No. 60N oil, and the mass ratio of white oil to solvent oil is 1:1 to 1:3.

[0011] The preparation of the above-mentioned oily polishing fluid includes the following steps: (1) First, mix the lubricant and base oil and ultrasonically stir for 5-30 minutes; (2) Then add anti-wear agent, wetting and dispersing agent, and sodium fatty amine polyoxyethylene ether sulfate to the system obtained in step (1) and continue ultrasonic stirring for 5-30 min; (3) Finally, add diamond micro powder and stir ultrasonically for 10-60 minutes. Observe the dispersion of diamond powder particles through a metallographic microscope.

[0012] During the overall ultrasonic stirring process, the ultrasonic frequency should be controlled between 40-80kHz, the stirring speed between 300-600rpm, and the stirring temperature between 25-30℃. Only by controlling the preparation of the grinding fluid within the above-mentioned range can the grinding fluid achieve better performance.

[0013] The significant advantages of this invention are: (1) The lubricant in this invention can reduce the friction between abrasive particles and the workpiece surface, prevent the workpiece surface from overheating, and avoid excessive wear or large-area scratches during the grinding process, which would cause the TTV value to increase beyond the reasonable range. (2) The wetting and dispersing agent in this invention can effectively reduce the surface tension of the grinding liquid. The particles in the grinding liquid are prone to agglomerate together. The wetting and dispersing agent is adsorbed on the surface of the particles, forming charge repulsion or steric hindrance, which prevents the particles from agglomerating, so that the abrasive is evenly dispersed and the grinding liquid is evenly distributed on the surface of the workpiece, avoiding the agglomeration of the grinding liquid that leads to local incomplete grinding and affects the grinding speed. (3) The anti-wear agent in this invention will react chemically or physically with the workpiece surface under the high pressure and high temperature generated during grinding, forming a tough protective film to protect the grinding disc from deep scratches. (4) The suspending agent in this invention stabilizes and disperses the grinding particles and controls the settling speed of the grinding particles. The density of the abrasive (such as alumina and diamond powder) in the oily grinding fluid is usually greater than that of the base oil. When it is left to stand or stored, it is easy to settle naturally, resulting in uneven concentration in the upper and lower parts of the grinding fluid. (5) The sodium polyoxyethylene ether sulfate of fatty amine in this invention has polyoxyethylene ether segments that extend in the solution, so that the particle surface has a certain charge. Due to electrostatic repulsion, the particles are difficult to aggregate, thereby achieving uniform dispersion of particles in the liquid, improving suspension stability, reducing the settling speed of the grinding liquid, and avoiding particle agglomeration that causes scratches during the grinding process.

[0014] (6) The oil-based polishing slurry for precision polishing of LED wafers of the present invention is applied during the precision polishing process of LED wafers. The temperature change of the polishing disc is relatively stable and there is no problem of overheating. At the same time, it improves the processing yield of precision polishing of LED wafers, increases polishing efficiency, reduces processing costs, and has little odor, is easy to clean, and is green and environmentally friendly. Attached Figure Description

[0015] Figure 1 This is a diagram showing the dispersion of data in Example 1.

[0016] Figure 2 This is a diagram showing the dispersion of Comparative Example 3.

[0017] Figure 3 This is a diagram showing the dispersion of data in Comparative Example 6. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0019] Example 1 (1) Synthesis of aliphatic amine polyoxyethylene ether ammonium sulfate:

[0020] Where n=5.

[0021] Add 263g of fatty amine polyoxyethylene ether (using AC1205 in the above reaction formula as an example) and 3g of urea to a four-necked flask. Turn on the mechanical stirrer and heat to 120°C using a heating mantle to melt and thoroughly mix the materials. Then add 42g of aminosulfonic acid to the flask. After the materials are added, maintain the temperature at 120°C and continue stirring for 6 hours until no obvious bubbles are generated in the system (the water produced in the reaction is collected through a reflux condenser or directly evaporated). After the reaction is complete, connect the system to a vacuum distillation apparatus and distill at a vacuum of 0.09MPa and a temperature of 130°C for 1.5 hours to remove unreacted trace amounts of raw materials and byproducts (such as water and residual aminosulfonic acid). After the system cools to room temperature, if there are small amounts of solid impurities (such as unreacted aminosulfonic acid), use a vacuum filtration apparatus (Buchner funnel + vacuum flask) to remove the solid impurities. The filtrate was transferred to a drying tray and dried in a drying oven at 90°C for 2.5 hours to obtain pure fatty amine polyoxyethylene ether ammonium sulfate product, which is the final fatty amine polyoxyethylene ether ammonium sulfate.

[0022] (2) Synthesis of sodium sulfate of fatty amine polyoxyethylene ether

[0023] Where n=5.

[0024] Add 105g of fatty amine polyoxyethylene ether ammonium sulfate to a three-necked flask, add 105g of anhydrous ethanol to dissolve it, and start magnetic stirring. Then slowly add 24g of sodium hydroxide solid, stirring until the materials are evenly mixed. Place the reaction system in a constant temperature water bath at 55℃ and stir for 2.5 hours. Ammonia gas will be generated during the reaction, which can be discharged through a condenser and absorbed as tail gas (using dilute sulfuric acid). After the reaction is complete, connect the system to a vacuum distillation apparatus and distill at a vacuum of 0.09MPa and a temperature of 65℃ to remove ethanol. After the residual liquid cools to room temperature, if there is a small amount of insoluble matter, filter it using a vacuum filtration device to remove solid impurities. Transfer the filtrate to a drying tray and dry it in a drying oven at 85℃ for 2.5 hours to obtain pure fatty amine polyoxyethylene ether sodium sulfate, the structural formula of which is as follows:

[0025] The structural characterization data are as follows: 1H NMR (300Mhz, DMSO-d6), δ: 0.88 (s, 3H, CH3), 1.26 (d, 12H, CH2), 1.27 (s, 2H, CH2), 1.26 (s, 2H, CH2), 1.29 (s, 2H, CH2), 1.36 (s, 2H, CH2), 3.01 (s, 2H, CH2), 2.51 (m, 4H, CH2), 3.51 (m, 4H, CH2), 3.52 (d, 24H, CH2), 3.54 (m, 4H, CH2), 3.70 (m, 4H, CH2); 13 C NMR (125Mhz, DMSO-d6), δ: 14.1, 22.7, 31.9, 29.3, 29.6, 29.3, 27.3, 28.3, 53.5, 54.2, 69.8, 70.1, 70.4, 70.1, 69.2, 68.1, 76.2, 78.2; HRMS calculated value C 32 H 65 NNa2O 16 S2: 829.35, measured value: 829.96.

[0026] The grinding fluid was prepared according to the components and amounts (by mass fraction, with the remainder being base oil) listed in Table 1. The specific preparation steps are as follows: (1) First, mix the lubricant and base oil and ultrasonically stir for 30 minutes; (2) Subsequently, anti-wear agent, wetting and dispersing agent, and surfactant sodium fatty amine polyoxyethylene ether sulfate were added and ultrasonic stirring was continued for 30 min; (3) Finally, add diamond micro powder and ultrasonically stir for 60 minutes. Observe the dispersion of diamond powder particles using a metallographic microscope. Figure 1 To be a grinding slurry with good dispersibility, Figure 2 It is a grinding slurry with poor dispersibility. Figure 3 It is a grinding fluid with average dispersing properties.

[0027] In steps (1) to (3), the ultrasonic frequency is 80kHz, the stirring speed is 600rpm, and the stirring temperature is 25℃. Table 1. Proportioning Table for Oily Grinding Fluids

[0028]

[0029] After preparing the mixture according to the proportions in Table 1, test the dispersibility, suspension, viscosity, polishing rate, TTV, and disk temperature change performance of the polishing slurry.

[0030] (1) Dispersion performance test: After preparing the mixture according to the proportions in Table 1, drop the drug solution onto the Mylar membrane, pour off the excess solution, and observe the dispersion of the drug particles remaining on the surface of the Mylar membrane. If the dispersion effect is as described above... Figure 1 The dispersion effect shown is good. If the dispersion effect is as shown... Figure 2 As shown, the dispersion effect is poor. If the dispersion performance is as shown... Figure 3 As shown, the dispersion effect is generally poor. (2) Suspension performance test: Prepare 550ml of drug solution according to Table 1 and put it into bottles of the same specification. Shake well and compare the settling height within the same time. If the settling height is 1-3cm within 1 hour, the suspension performance is good; if the settling height is 5-8cm within 1 hour, the suspension performance is average; if the settling height is 10-15cm within 1 hour, the suspension performance is poor. (3) Viscosity performance test: After preparing the medicine solution according to Table 1, the temperature is controlled at 25℃ and the viscosity is tested with a No. 0 rotor at 60rpm. The viscosity of a single sample is obtained by three parallel tests. (4) Polishing rate: After grinding, heat to 100℃ and remove the sapphire sheet. Clean the sapphire sheet with wax remover, water and IPA in sequence. Use a micrometer thickness gauge to test 5 points of the sapphire sheet again and record the average value. Material removal rate = difference in thickness before and after average value μm / time min; (5) TTV test: In the dispersion test, the difference between the maximum and minimum thickness at 5 points after grinding is taken as the TTV value in μm.

[0031] Table 2. Comprehensive evaluation of the performance of the grinding fluid

[0032] As can be seen from Tables 1-2, the oily polishing fluid of the present invention can ensure effective polishing performance under suitable preparation conditions, maintain a good polishing rate during the polishing process, effectively reduce polishing temperature and scratches, control polishing disc temperature, improve polishing efficiency and reduce processing costs.

[0033] Compared with Example 1, the ratio of base oil to solvent oil in Comparative Example 1 was increased from 1:1 to 1:3. Under the same conditions of grinding slurry preparation and grinding time, the viscosity of the grinding slurry was too low, which made it easy for the grinding slurry to be thrown out during the grinding process, leaving less liquid on the grinding disc and affecting the processing speed. Compared with Example 1, the proportion of wetting and dispersing agent in Comparative Example 2 was increased by 1 times, resulting in poor dispersion performance. The uneven dispersion of the grinding powder easily led to powder agglomeration or accumulation, which in turn caused scratches, increased surface roughness, and increased TTV during the grinding process. Compared with Example 1, Comparative Example 3 did not add sodium polyoxyethylene ether sulfate with fatty amines, resulting in poorer dispersion and suspension properties, and a relatively higher grinding disc temperature. During the grinding process, the poor suspension properties led to a faster settling speed of the grinding liquid. In addition, the weak dispersion properties affected the overall dispersion uniformity of the grinding liquid and the grinding speed, thereby reducing the grinding efficiency, prolonging the grinding time, increasing the grinding disc temperature, increasing the surface roughness, and increasing the TTV. Compared with Example 1, the proportion of lubricant in Comparative Example 4 was reduced by half, resulting in reduced lubrication performance. Unstable frictional resistance caused the cutting rate of the abrasive particles on the wafer to fluctuate, making it impossible to accurately control the wafer thinning amount. This could lead to situations where some areas are too thin and others do not reach the target thickness. Compared with Example 1, the proportion of anti-wear agent in Comparative Example 5 was reduced by half, resulting in decreased anti-wear performance, significantly increased scratches, and significantly increased TTV. Compared with Example 1, Comparative Example 6 did not add sodium polyoxyethylene ether sulfate with fatty amines, and the wetting and dispersing agent was increased by 1 time, but the dispersion performance was generally poor, the grinding disc temperature was still relatively high, and the TTV exceeded the reasonable range, which remained in the range of 6-7. Compared with Example 1, the proportion of suspending agent in Comparative Example 7 was reduced by half. The settling speed of the grinding liquid was faster, and the particles that were not stably suspended would quickly settle to the bottom of the grinding chamber and could not fully contact and collide with the grinding media (such as zirconium beads), resulting in over-grinding of the bottom particles, while there were almost no effective particles in the upper liquid, and the grinding effect was polarized.

[0034] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. An oil-based polishing slurry for precision polishing of LED wafers, characterized in that, The product is made from the following raw materials in the following mass percentages, with the sum of the mass percentages being 100%: 8-15% lubricant, 0.5-5% wetting and dispersing agent, 0.5-5% anti-wear agent, 0.5-5% sodium sulfate of fatty amine polyoxyethylene ether, 0.5-6% suspending agent, 0.5-3% diamond micro powder, and the balance being base oil. The structure of the fatty amine polyoxyethylene ether sodium sulfate is shown below: , where n = 1~5.

2. The oily polishing fluid according to claim 1, characterized in that, The lubricant is one or more of butyl stearate, isopropyl palmitate, glyceryl tristearate, and triethanolamine oleate soap.

3. The oily polishing fluid according to claim 1, characterized in that, The wetting and dispersing agent is one or more of sodium alkylbenzene sulfonate, polymethyl methacrylate, monoalkyl phosphate, and polyoxyethylene ether phosphate.

4. The oily polishing fluid according to claim 1, characterized in that, The anti-wear agent is one or more of p-phenylenediamine, ethylenediamine, diethanolamine, triethanolamine, and aniline.

5. The oily polishing fluid according to claim 1, characterized in that, The suspending agent shown is any one or more of organobentonite, polyacrylamide, sodium carboxymethyl cellulose, and sodium metasilicate.

6. The oily polishing fluid according to claim 1, characterized in that, The diamond micropowder shown has a particle size of 0.3~3 μm.

7. The oily polishing fluid according to claim 1, characterized in that, The base oil includes white oil and solvent oil, wherein the solvent oil is No. 60N oil, and the mass ratio of white oil to solvent oil is 1:1 to 1:

3.

8. The method for preparing the oily polishing fluid according to any one of claims 1-7, characterized in that, Includes the following steps: Mix the lubricant and base oil with ultrasonic stirring for 5-30 minutes; Add anti-wear agent and wetting and dispersing agent to the system obtained in step (1), and continue ultrasonic stirring for 5-30 min with sodium fatty amine polyoxyethylene ether sulfate. Finally, add diamond micro powder and ultrasonically stir for 10-60 minutes. Observe the dispersion of diamond powder particles using a metallographic microscope.

9. The preparation method according to claim 8, characterized in that: In steps (1) to (3), the ultrasonic frequency is 40 to 80 kHz, the stirring speed is 300 to 600 rpm, and the stirring temperature is 25 to 30 ℃.

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