Core-shell grinding material with water-soluble shell, polishing disc and preparation method and application of core-shell grinding material

Abstract

The invention discloses a core-shell grinding material with a water-soluble shell, a polishing disc and a preparation method and application of the core-shell grinding material and the polishing disc, and belongs to the technical field of precision machining. The core-shell grinding material of the water-soluble shell is composed of a grinding material inner layer and a water-soluble inorganic salt outer layer, the core-shell grinding material and the grinding material inner layer are both granular, and the water-soluble inorganic salt outer layer comprises one or more of sodium chloride, sodium sulfate or barium chloride. The core-shell grinding material with the water-soluble shell exists in a polishing disc in a consolidation mode before polishing, in the workpiece polishing process, along with dropwise adding of the deionized water-based polishing solution, the shell of the core-shell grinding material is rapidly dissolved, and the grinding material exists in limited space pores generated by dissolution of the shell in a free mode. Due to the fact that the holes have a limiting effect on the grinding materials, waste of the grinding materials is reduced, damage of the grinding materials to the surface / subsurface of the workpiece is reduced, and finally the atomic-scale surface roughness is obtained.

Description

Technical Field

[0001] This invention belongs to the field of precision machining technology, and relates to a water-soluble core-shell abrasive, a polishing disc, its preparation method, and its application. Background Technology

[0002] In the field of precision machining technology, with the rapid development of high-end manufacturing industries such as electronics, aerospace, and optical instruments, increasingly stringent requirements are being placed on the surface accuracy, flatness, and processing efficiency of workpieces. For example, in the processing of precision components such as semiconductor wafers and laser lenses, polishing processes are often required to achieve nanometer-level or even atomic-level surface quality control. Polishing discs and abrasives, as the core consumables of this process, directly affect the processing accuracy and yield of the final product.

[0003] During the polishing process, polishing methods can be classified into bonded abrasive polishing, semi-bonded abrasive polishing, and free abrasive polishing according to the movement state and action mode of the abrasive.

[0004] Bonded abrasive polishing involves fixing abrasive particles to a polishing disc using a binder. The particles cannot move freely, and polishing is achieved through the overall contact between the polishing disc and the workpiece surface. The advantages of bonded abrasive polishing include high processing efficiency, a fixed processing trajectory, and good processing uniformity. The binder-fixed abrasive particles are suitable for rough polishing. However, because bonded abrasives lack elasticity during contact with the workpiece, they are prone to surface / subsurface damage. Furthermore, inconsistent edge heights mean that abrasive particles with higher edge heights play a dominant cutting role, and the edges are easily worn down, requiring frequent disc dressing and resulting in a short polishing disc lifespan.

[0005] Semi-bonded abrasive polishing involves abrasive particles being partially fixed to the polishing disc by a weak binder, existing in a state between bonded and free abrasives. During polishing, the abrasive particles are loosely bound by the weak binder, maintaining a certain degree of integrity while allowing relative movement or detachment under stress. The advantages of semi-bonded abrasive polishing are a balance between removal efficiency and flexibility. The abrasive particles are loosely bound by the weak binder, resulting in higher material removal efficiency than free abrasives. It also exhibits good self-sharpening properties, with the abrasive particles automatically detaching after wear. However, it has a shorter lifespan, faster disc wear, higher long-term operating costs, and a machining accuracy between bonded and free abrasives, making it difficult to achieve atomic-level ultra-precision requirements.

[0006] Free abrasive polishing involves abrasive particles existing in a loose, unconsolidated state, typically suspended in a liquid medium. These particles can flow, roll, or slide freely during the polishing process. The advantages of free abrasive polishing include high machining accuracy, the ability of the particles to roll and slide freely, good flexibility, and flexible particle size adjustment, making it commonly used for fine polishing. However, it suffers from low efficiency, poor processing uniformity, slow material removal speed, and high cost. Furthermore, waste disposal and abrasive recycling are difficult, and it can easily cause pollution.

[0007] The current patent (CN 101450463 A) discloses a self-generating porosity superhard abrasive grinding wheel and its dressing method. A "soluble" filler, soluble in a specific solvent, is added to the grinding wheel. Adding the specific solvent to the grinding wheel surface causes the "soluble" filler to dissolve and form pores. Here, the "soluble" filler and the abrasive are in a separate state, still acting as solidified abrasive, which easily causes surface / subsurface damage to the workpiece. Furthermore, the appearance of pores damages the matrix, resulting in a short grinding wheel lifespan.

[0008] The current patent (CN 118438342 A) discloses a core-shell abrasive polishing disc that can change the movement state of abrasive particles, its preparation method, and its application. By adding an organic solvent to the polishing solution, the colloidal outer shell of the core-shell abrasive on the surface of the polishing disc is dissolved, allowing the internal abrasive particles to move freely within the limited pores created by the dissolved outer shell. Here, the abrasive particles change from a solidified state to a free state, while avoiding the waste of free abrasive particles. However, this core-shell abrasive forms its shell through adhesion, resulting in a thin and difficult-to-control coating thickness. The resulting pores are small, restricting the movement of abrasive particles within the pores and making them prone to detachment. Furthermore, it requires the addition of an organic solvent for dissolution, and the dissolution rate is relatively slow, failing to quickly transform the abrasive particles from a solidified state to a free state within the pores. Additionally, some solidified abrasive particles still act during processing, potentially causing surface / subsurface damage to the workpiece.

[0009] Therefore, how to develop a core-shell abrasive, polishing disc, and its preparation method and application that reduces the cost of polishing, improves surface quality, and is environmentally friendly and has a water-soluble outer shell is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0010] To address the problems existing in the prior art, this invention discloses a water-soluble core-shell abrasive, a polishing disc, its preparation method, and its application. A water-soluble shell is coated onto the surface of the abrasive to form a core-shell abrasive, which exists in a solidified form within the polishing disc before polishing. By adding deionized water-based polishing fluid, the shell is dissolved to form larger pores, altering the movement and action of the abrasive during the polishing process. This maintains effective cutting action and solves the problems of small pores formed by dissolving core-shell abrasives, requiring the addition of organic solvents for dissolution, slow dissolution rates, inability to quickly transform the abrasive from a solidified state to a porous, free state, and short polishing disc lifespan.

[0011] The water-soluble shell abrasive, polishing disc, preparation method, and application of this invention are of great significance for reducing the cost of polishing, improving surface quality, and being environmentally friendly.

[0012] In view of this, the present invention provides a core-shell abrasive with a water-soluble outer shell, a polishing disc, a method for preparing the same, and its application.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] A core-shell abrasive with a water-soluble outer shell, comprising an inner abrasive layer and an outer water-soluble inorganic salt layer, wherein both the core-shell abrasive and the inner abrasive layer are granular, the average particle size of the core-shell abrasive is 0.2-12 μm, the average particle size of the inner abrasive layer is 0.1-10 μm, and the average thickness of the outer water-soluble inorganic salt layer is 0.05-2 μm;

[0015] The outer layer of the water-soluble inorganic salt includes one or more of sodium chloride, sodium sulfate, or barium chloride.

[0016] Furthermore, the inner layer of the abrasive includes one or more of diamond, alumina, cerium oxide, silicon dioxide, or silicon carbide.

[0017] The present invention also provides a method for preparing the core-shell abrasive with the water-soluble outer shell, comprising the following steps:

[0018] (1) At 20-30℃, deionized water and surfactant are mixed with a mass ratio of (500-10000):1. The mixture is ultrasonically dispersed with a power of 60w and simultaneously mechanically stirred at 200r / min for 1-2min until the surfactant is completely dissolved to obtain an aqueous solution of surfactant.

[0019] (2) The surfactant aqueous solution and water-soluble inorganic salt obtained in step (1) are mixed in a mass ratio of (71-84):(16-29), ultrasonically dispersed at a power of 60w, and simultaneously mechanically stirred at 200r / min for 1-2min until all water-soluble inorganic salt is dissolved to obtain a saturated solution of water-soluble inorganic salt.

[0020] (3) Mix the abrasive with the saturated solution of water-soluble inorganic salt obtained in step (2), and control the mass ratio of abrasive to water-soluble inorganic salt to solute to be (0.125-1):1. Disperse the mixture with ultrasonic power of 60W and simultaneously stir mechanically at 200r / min for 1-2min. Then, under the heating condition of 70-110℃, stir at 200-600r / min until the solution is completely evaporated to obtain the core-shell abrasive semi-finished product.

[0021] (4) Place the core-shell abrasive semi-finished product obtained in step (3) in a drying oven at 60-80℃ for 1-2 hours, grind the dried core-shell abrasive, and then sieve it through a 200-1000 mesh screen to obtain a uniformly dispersed water-soluble core-shell abrasive.

[0022] Furthermore, in step (1), the surfactant includes any one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or polyethylene glycol.

[0023] The present invention also provides a water-soluble shell core-shell abrasive polishing disc, comprising the water-soluble shell core-shell abrasive or the water-soluble shell core-shell abrasive prepared by the method and a polishing disc substrate.

[0024] Furthermore, the polishing disc substrate includes epoxy resin-based or polyurethane-based materials.

[0025] The present invention also provides a method for preparing the core-shell abrasive polishing disc with the water-soluble outer shell, comprising the following steps:

[0026] 1) Mix the water-soluble core-shell abrasive with the polishing disc substrate to obtain a mixture. The mass percentage of the water-soluble core-shell abrasive in the mixture is 5-10%. Pour the mixture into the polishing disc mold and solidify it to obtain a semi-finished polishing disc.

[0027] 2) The surface of the semi-finished polishing disc obtained in step 1) is finished with a grinding wheel to ensure that the surface of the polishing disc has a flatness of ±0.01mm, thus obtaining the water-soluble shell core-shell abrasive polishing disc.

[0028] Furthermore, when the polishing pad substrate is epoxy resin-based, step 1) is as follows:

[0029] Weigh each raw material according to the following mass percentages: 5-10% for water-soluble core-shell abrasive, 70-74% for epoxy resin, and 20-21% for curing agent;

[0030] Mix the water-soluble core-shell abrasive with epoxy resin and stir at 1000-1200 r / min for 30-60 min. Then add the curing agent and stir at 1000-1200 r / min for 5-10 min to obtain a mixture. Pour the mixture into a polishing disc mold and let it stand and cure at 23-26℃ for 10-12 h.

[0031] The curing agent includes any one of T31, ethylenediamine, cyclohexylamine, or polyamide ester.

[0032] Furthermore, when the polishing pad substrate is polyurethane-based, step 1) is as follows:

[0033] Weigh each raw material according to the following mass percentages: 5-10% water-soluble core-shell abrasive, 65-75% polyurethane prepolymer, 20-25% hydroxypropyl silicone oil, 0.001% stannous octoate, and 1-2% chain extender MOCA.

[0034] Water-soluble core-shell abrasive, polyurethane prepolymer, hydroxypropyl silicone oil and stannous octoate are mixed and ultrasonically dispersed at 60W at 70-80℃, while stirring at 500-600r / min for 20min. Then, chain extender MOCA is added, and the stirring speed is increased to 1000-1200r / min for 30s to obtain a mixture. The mixture is injected into a polytetrafluoroethylene-coated mold and a pressure of 2kg is applied. The mixture is then allowed to stand and cure at 115℃ for 16h.

[0035] The present invention also provides a core-shell abrasive polishing disc with a water-soluble shell or a core-shell abrasive polishing disc with a water-soluble shell prepared by the method for use in workpiece polishing.

[0036] The water-soluble core-shell abrasive of this invention exists in a solidified form in the polishing disc before polishing. During the workpiece polishing process, as deionized water-based polishing fluid is added, the outer shell of the core-shell abrasive rapidly dissolves, allowing the abrasive to exist in a free form within the limited pores created by the dissolution of the outer shell. Because the pores confine the abrasive, abrasive waste is reduced, and damage to the workpiece surface / subsurface is minimized, ultimately achieving atomic-level surface roughness.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] (1) The water-soluble shell abrasive provided by the present invention consists of an inner abrasive layer and an outer water-soluble inorganic salt layer. The preparation process is simple and convenient, without the need for complex reactions, and the thickness of the water-soluble shell can be controlled by adjusting the process.

[0039] (2) The water-soluble shell abrasive polishing disc provided by the present invention can quickly dissolve the shell of the core shell abrasive and move in the pores in a free form during polishing. This can avoid the situation where slow dissolution or incomplete dissolution causes some abrasive to remain in a solidified or semi-solidified state, which can damage the surface / subsurface of the workpiece.

[0040] (3) The water-soluble shell abrasive polishing disc provided by the present invention has a simple solvent system required for the core-shell abrasive to change from a solidified state to a free state, without the need to add other solvents, and is easy to process and environmentally friendly.

[0041] (4) The water-soluble shell abrasive polishing disc provided by the present invention has large pores generated by the dissolution of the shell abrasive during polishing, and the abrasive is not easy to fall off, which can better avoid the problem of abrasive waste.

[0042] (5) The water-soluble shell abrasive polishing disc provided by the present invention moves in the pores in a free form during polishing. In the initial stage, the abrasive with a high edge height plays the main cutting role. After processing for a period of time, the abrasive with a high edge height becomes dull and the pores become larger under the action of the abrasive. The edge height of the abrasive decreases and the cutting action weakens. The abrasive with a low edge height and not dulled plays the main cutting role. Therefore, frequent disc repair is not required, which improves the service life of the polishing disc. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the preparation process of the core-shell abrasive for the water-soluble outer shell of the present invention.

[0044] Figure 2 A schematic diagram of the overall structure of the polishing disc for consolidating the core-shell abrasive of the water-soluble outer shell of the present invention.

[0045] Figure 3 A schematic diagram of the processing flow of the core-shell abrasive polishing disc with a water-soluble outer shell provided by the present invention.

[0046] Among them, Figure 1-3 In the diagram, 1 represents the abrasive, 2 represents the saturated solution of water-soluble inorganic salt, 3 represents the stirring rod, 4 represents the core-shell abrasive, 5 represents the inner layer of the abrasive, 6 represents the outer layer of water-soluble inorganic salt, 7 represents the polishing disc substrate, 8 represents the deionized water-based polishing fluid, 9 represents the pores, 10 represents the workpiece, 11 represents the direction of workpiece movement, and 12 represents the passivating abrasive. Detailed Implementation

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The raw materials for the embodiments and comparative examples of this invention: the epoxy resin was manufactured by Hangzhou Wuhuigang Adhesive Co., Ltd., and the model was E51;

[0049] The manufacturer of hardener T31 is Hangzhou Wuhuigang Adhesive Co., Ltd.

[0050] The polyurethane prepolymer is manufactured by Jining Baichuan Chemical Co., Ltd., and its model is TDI-PTMEG; the hydroxypropyl silicone oil is manufactured by Jiande Juhe New Materials Co., Ltd., and its model is JHY-20 with a molecular weight of 2000.

[0051] The chain extender MOCA is manufactured by Jining Baichuan Chemical Co., Ltd.

[0052] The manufacturer of stannous octoate is Shanghai Aladdin Biochemical Technology Co., Ltd.

[0053] Examples 1-9 are core-shell abrasive polishing discs with an epoxy resin-based water-soluble shell. The water-soluble shell abrasive consists of an inner abrasive layer and an outer layer of water-soluble inorganic salt, with the inner abrasive layer being diamond. The abrasive particle size and water-soluble inorganic salt differ in Examples 1-9; Comparative Example 1 is an epoxy resin-based diamond abrasive polishing disc. Parameters for Examples 1-9 and Comparative Example 1 are shown in Table 1.

[0054] Table 1. Summary of some parameters in Examples 1-9 and Comparative Example 1

[0055]

[0056] Example 1

[0057] The core-shell abrasive with a water-soluble outer shell consists of an inner abrasive layer and an outer water-soluble inorganic salt layer. Both the core-shell abrasive and the inner abrasive layer are granular. The average particle size of the core-shell abrasive is 9 μm, the average particle size of the inner abrasive layer is 5 μm, and the average thickness of the outer water-soluble inorganic salt layer is 2 μm. The outer water-soluble inorganic salt layer is sodium sulfate, and the inner abrasive layer is diamond.

[0058] like Figure 1 As shown, the method for preparing a water-soluble core-shell abrasive includes the following steps:

[0059] (1) At 25°C, deionized water and surfactant sodium dodecyl sulfate were added to a polytetrafluoroethylene beaker and mixed. The mass ratio of deionized water to surfactant was 10000:1. The mixture was ultrasonically dispersed at a power of 60W and simultaneously mechanically stirred at 200r / min for 1min until the surfactant was completely dissolved, thus obtaining an aqueous solution of surfactant.

[0060] (2) The surfactant aqueous solution obtained in step (1) and the water-soluble inorganic salt anhydrous sodium sulfate are mixed at a mass ratio of 78:22, ultrasonically dispersed at a power of 60w, and simultaneously mechanically stirred at 200r / min for 2min until all the water-soluble inorganic salt is dissolved to obtain a saturated solution of water-soluble inorganic salt.

[0061] (3) Mix the diamond abrasive with a particle size of 5μm with the water-soluble inorganic salt saturated solution obtained in step (2), control the mass ratio of abrasive to anhydrous sodium sulfate to solute to be 0.25:1, disperse it ultrasonically with a power of 60w, and simultaneously stir it mechanically at 200r / min for 2min. Then, under the heating condition of 90℃, stir it at 400r / min until the solution is completely evaporated to obtain the core-shell abrasive semi-finished product.

[0062] (4) Place the semi-finished core-shell abrasive obtained in step (3) in a drying oven at 60°C for 1 hour, grind the dried core-shell abrasive with a mortar and pestle, and then sieve it with a 400-mesh sieve to obtain a uniformly dispersed water-soluble core-shell abrasive.

[0063] The overall structure of the water-soluble core-shell abrasive polishing disc is as follows: Figure 2 As shown, the abrasive includes a water-soluble shell and a polishing disc substrate, the polishing disc substrate being epoxy resin-based.

[0064] A method for preparing a core-shell abrasive polishing disc with a water-soluble outer shell includes the following steps:

[0065] 1) Weigh each raw material according to the following mass percentages: 10% for water-soluble core-shell abrasive, 70% for epoxy resin, and 20% for curing agent T31;

[0066] The water-soluble core-shell abrasive and epoxy resin were mixed and stirred at 1000 r / min for 30 min. Then, the curing agent was added and mixed and stirred at 1000 r / min for 5 min to obtain a mixture. The mixture was poured into a polishing disc mold and allowed to stand and cure at 25°C for 12 h.

[0067] 2) The surface of the semi-finished polishing disc obtained in step 1) is finished with a grinding wheel. The polishing disc is installed on the polishing machine and rotated at low speed. The grinding wheel is gently contacted with the rotating disc surface to remove the residual polishing agent, debris and hardened layer on the disc surface. During the process, the grinding wheel is kept in stable contact with the disc surface to avoid excessive force that could damage the disc surface. After the disc surface is restored to flatness and there are no obvious stains or foreign objects, the polishing machine is turned off and the polishing disc is removed. Ensure that the surface of the polishing disc has a high flatness of ±0.01mm to obtain a water-soluble core-shell abrasive polishing disc.

[0068] Example 2

[0069] The difference from Example 1 is that the diamond abrasive particle size in step (3) of this example is 1 μm, while the other steps are the same.

[0070] Example 3

[0071] The difference from Example 1 is that the diamond abrasive particle size in step (3) of this example is 3μm, while the other steps are the same.

[0072] Example 4

[0073] The difference from Example 1 is that the outer layer of the water-soluble inorganic salt is sodium chloride.

[0074] The core-shell abrasive with a water-soluble outer shell consists of an inner abrasive layer and an outer water-soluble inorganic salt layer. Both the core-shell abrasive and the inner abrasive layer are granular. The average particle size of the core-shell abrasive is 9 μm, the average particle size of the inner abrasive layer is 5 μm, and the average thickness of the outer water-soluble inorganic salt layer is 2 μm. The outer water-soluble inorganic salt layer is sodium chloride, and the inner abrasive layer is diamond.

[0075] like Figure 1 As shown, the method for preparing a water-soluble core-shell abrasive includes the following steps:

[0076] (1) At 25°C, deionized water and surfactant sodium dodecyl sulfate were added to a polytetrafluoroethylene beaker and mixed. The mass ratio of deionized water to surfactant was 10000:1. The mixture was ultrasonically dispersed at a power of 60W and simultaneously mechanically stirred at 200r / min for 1min until the surfactant was completely dissolved, thus obtaining an aqueous solution of surfactant.

[0077] (2) The surfactant aqueous solution obtained in step (1) and the water-soluble inorganic salt sodium chloride are mixed at a mass ratio of 100:36, ultrasonically dispersed at a power of 60w, and simultaneously mechanically stirred at 200r / min for 2min until all the water-soluble inorganic salt is dissolved to obtain a saturated solution of water-soluble inorganic salt.

[0078] (3) Mix the diamond abrasive with a particle size of 5μm with the water-soluble inorganic salt saturated solution obtained in step (2), control the mass ratio of abrasive to sodium chloride solute to be 0.25:1, disperse it ultrasonically with a power of 60w, and simultaneously stir it mechanically at 200r / min for 2min. Then, under the heating condition of 90℃, stir at 400r / min until the solution is completely evaporated to obtain the core-shell abrasive semi-finished product.

[0079] (4) Place the semi-finished core-shell abrasive obtained in step (3) in a drying oven at 60°C for 1 hour, grind the dried core-shell abrasive with a mortar and pestle, and then sieve it with a 400-mesh sieve to obtain a uniformly dispersed water-soluble core-shell abrasive.

[0080] The overall structure of the water-soluble core-shell abrasive polishing disc is as follows: Figure 2 As shown, the polishing disc includes a core-shell abrasive with a water-soluble outer shell and a polishing pad substrate, the polishing pad substrate being epoxy resin-based. The preparation method of the water-soluble core-shell abrasive polishing disc is the same as in Example 1.

[0081] Example 5

[0082] The difference from Example 4 is that the diamond abrasive particle size in step (3) of this example is 1 μm, while the other steps are the same.

[0083] Example 6

[0084] The difference from Example 4 is that the diamond abrasive particle size in step (3) of this example is 3μm, while the other steps are the same.

[0085] Example 7

[0086] The difference from Example 1 is that the outer layer of the water-soluble inorganic salt is barium chloride.

[0087] The core-shell abrasive with a water-soluble outer shell consists of an inner abrasive layer and an outer water-soluble inorganic salt layer. Both the core-shell abrasive and the inner abrasive layer are granular. The average particle size of the core-shell abrasive is 9 μm, the average particle size of the inner abrasive layer is 5 μm, and the average thickness of the outer water-soluble inorganic salt layer is 2 μm. The outer water-soluble inorganic salt layer is barium chloride, and the inner abrasive layer is diamond.

[0088] like Figure 1 As shown, the method for preparing a water-soluble core-shell abrasive includes the following steps:

[0089] (1) At 25°C, deionized water and surfactant sodium dodecyl sulfate were added to a polytetrafluoroethylene beaker and mixed. The mass ratio of deionized water to surfactant was 10000:1. The mixture was ultrasonically dispersed at a power of 60W and simultaneously mechanically stirred at 200r / min for 1min until the surfactant was completely dissolved, thus obtaining an aqueous solution of surfactant.

[0090] (2) The surfactant aqueous solution obtained in step (1) and the water-soluble inorganic salt barium chloride are mixed at a mass ratio of 100:36, ultrasonically dispersed at a power of 60w, and simultaneously mechanically stirred at 200r / min for 2min until all the water-soluble inorganic salt is dissolved to obtain a saturated solution of water-soluble inorganic salt.

[0091] (3) Mix the diamond abrasive with a particle size of 5μm with the water-soluble inorganic salt saturated solution obtained in step (2), control the mass ratio of abrasive to barium chloride solute to be 0.25:1, disperse it ultrasonically with a power of 60w, and simultaneously stir it mechanically at 200r / min for 2min. Then, under the heating condition of 90℃, stir it at 400r / min until the solution is completely evaporated to obtain the core-shell abrasive semi-finished product.

[0092] (4) Place the semi-finished core-shell abrasive obtained in step (3) in a drying oven at 60°C for 1 hour, grind the dried core-shell abrasive with a mortar and pestle, and then sieve it with a 400-mesh sieve to obtain a uniformly dispersed water-soluble core-shell abrasive.

[0093] The overall structure of the water-soluble core-shell abrasive polishing disc is as follows: Figure 2 As shown, the polishing disc includes a core-shell abrasive with a water-soluble outer shell and a polishing pad substrate, the polishing pad substrate being epoxy resin-based. The preparation method of the water-soluble core-shell abrasive polishing disc is the same as in Example 1.

[0094] Example 8

[0095] The difference from Example 7 is that the diamond abrasive particle size in step (3) of this example is 1 μm, while the other steps are the same.

[0096] Example 9

[0097] The difference from Example 7 is that the diamond abrasive particle size in step (3) of this example is 3μm, while the other steps are the same.

[0098] Comparative Example 1

[0099] The method for preparing a polishing disc includes the following steps:

[0100] 1) Weigh each raw material according to the following mass percentages: 10% diamond abrasive with a particle size of 5μm, 70% epoxy resin, and 20% curing agent T31;

[0101] Diamond abrasive and epoxy resin are mixed and stirred at 1000 r / min for 30 min. Then, curing agent T31 is added and mixed and stirred at 1000 r / min for 5 min to obtain a mixture. The mixture is poured into a polishing disc mold and allowed to stand and cure at 25°C for 12 h.

[0102] 2) Use a grinding wheel to finish the surface of the semi-finished polishing disc obtained in step 1) to ensure that the surface of the polishing disc has a high flatness of ±0.01mm, and thus obtain the polishing disc.

[0103] Examples 10-18 are polyurethane-based water-soluble shell core-shell abrasive polishing discs. The water-soluble shell core-shell abrasive consists of an inner abrasive layer and an outer layer of water-soluble inorganic salt. The inner abrasive layer is diamond. The abrasive particle size and water-soluble inorganic salt differ in Examples 10-18; Comparative Example 2 is a polyurethane-based diamond abrasive polishing disc.

[0104] The parameters for Examples 10-18 and Comparative Example 2 are shown in Table 2:

[0105] Table 2. Summary of parameters for Examples 10-18 and Comparative Example 2

[0106]

[0107]

[0108] Example 10

[0109] The core-shell abrasive with a water-soluble outer shell consists of an inner abrasive layer and an outer water-soluble inorganic salt layer. Both the core-shell abrasive and the inner abrasive layer are granular. The average particle size of the core-shell abrasive is 9 μm, the average particle size of the inner abrasive layer is 5 μm, and the average thickness of the outer water-soluble inorganic salt layer is 2 μm. The outer water-soluble inorganic salt layer is sodium sulfate, and the inner abrasive layer is diamond.

[0110] like Figure 1 As shown, the method for preparing a water-soluble core-shell abrasive includes the following steps:

[0111] (1) At 25°C, deionized water and surfactant sodium dodecyl sulfate were added to a polytetrafluoroethylene beaker and mixed. The mass ratio of deionized water to surfactant was 10000:1. The mixture was ultrasonically dispersed at a power of 60W and simultaneously mechanically stirred at 200r / min for 1min until the surfactant was completely dissolved, thus obtaining an aqueous solution of surfactant.

[0112] (2) The surfactant aqueous solution obtained in step (1) and the water-soluble inorganic salt anhydrous sodium sulfate are mixed at a mass ratio of 78:22, ultrasonically dispersed at a power of 60w, and simultaneously mechanically stirred at 200r / min for 2min until all the water-soluble inorganic salt is dissolved to obtain a saturated solution of water-soluble inorganic salt.

[0113] (3) Mix the diamond abrasive with a particle size of 5μm with the water-soluble inorganic salt saturated solution obtained in step (2), control the mass ratio of abrasive to anhydrous sodium sulfate to solute to be 0.25:1, disperse it ultrasonically with a power of 60w, and simultaneously stir it mechanically at 200r / min for 2min. Then, under the heating condition of 90℃, stir it at 400r / min until the solution is completely evaporated to obtain the core-shell abrasive semi-finished product.

[0114] (4) Place the semi-finished core-shell abrasive obtained in step (3) in a drying oven at 60°C for 1 hour, grind the dried core-shell abrasive with a mortar and pestle, and then sieve it with a 400-mesh sieve to obtain a uniformly dispersed water-soluble core-shell abrasive.

[0115] The overall structure of the water-soluble core-shell abrasive polishing disc is as follows: Figure 2 As shown, the abrasive includes a water-soluble shell and a polishing disc substrate, the polishing disc substrate being epoxy resin-based.

[0116] A method for preparing a core-shell abrasive polishing disc with a water-soluble outer shell includes the following steps:

[0117] 1) Weigh each raw material according to the following mass percentages: 10% water-soluble core-shell abrasive, 70% polyurethane prepolymer, 18% hydroxypropyl silicone oil, 0.001% stannous octoate, and 1.9% chain extender MOCA;

[0118] Water-soluble core-shell abrasive, polyurethane prepolymer, hydroxypropyl silicone oil and stannous octoate were mixed and ultrasonically stirred at 600 r / min for 20 min at 70 °C. Then, chain extender MOCA was added and the stirring speed was increased to 1000 r / min for 30 s to obtain a mixture. The mixture was injected into a mold coated with polytetrafluoroethylene and a pressure of 2 kg was applied. The mixture was allowed to stand and cure at 115 °C for 16 h.

[0119] 2) The surface of the semi-finished polishing disc obtained in step 1) is finished with a grinding wheel. The polishing disc is installed on the polishing machine and rotated at low speed. The grinding wheel is gently contacted with the rotating disc surface to remove the residual polishing agent, debris and hardened layer on the disc surface. During the process, the grinding wheel is kept in stable contact with the disc surface to avoid excessive force that could damage the disc surface. After the disc surface is restored to flatness and there are no obvious stains or foreign objects, the polishing machine is turned off and the polishing disc is removed. Ensure that the surface of the polishing disc has a high flatness of ±0.01mm to obtain a water-soluble core-shell abrasive polishing disc.

[0120] Example 11

[0121] The difference from Example 10 is that the diamond abrasive particle size in step (3) of this example is 1 μm, while the other steps are the same.

[0122] Example 12

[0123] The difference from Example 10 is that the diamond abrasive particle size in step (3) of this example is 3μm, while the other steps are the same.

[0124] Example 13

[0125] The difference from Example 10 is that the outer layer of the water-soluble inorganic salt is sodium chloride.

[0126] The core-shell abrasive with a water-soluble outer shell consists of an inner abrasive layer and an outer water-soluble inorganic salt layer. Both the core-shell abrasive and the inner abrasive layer are granular. The average particle size of the core-shell abrasive is 9 μm, the average particle size of the inner abrasive layer is 5 μm, and the average thickness of the outer water-soluble inorganic salt layer is 2 μm. The outer water-soluble inorganic salt layer is sodium chloride, and the inner abrasive layer is diamond.

[0127] like Figure 1 As shown, the method for preparing a water-soluble core-shell abrasive includes the following steps:

[0128] (1) At 25°C, deionized water and surfactant sodium dodecyl sulfate were added to a polytetrafluoroethylene beaker and mixed. The mass ratio of deionized water to surfactant was 10000:1. The mixture was ultrasonically dispersed at a power of 60W and simultaneously mechanically stirred at 200r / min for 1min until the surfactant was completely dissolved, thus obtaining an aqueous solution of surfactant.

[0129] (2) The surfactant aqueous solution obtained in step (1) and the water-soluble inorganic salt sodium chloride are mixed at a mass ratio of 100:36, ultrasonically dispersed at a power of 60w, and simultaneously mechanically stirred at 200r / min for 2min until all the water-soluble inorganic salt is dissolved to obtain a saturated solution of water-soluble inorganic salt.

[0130] (3) Mix the diamond abrasive with a particle size of 5μm with the water-soluble inorganic salt saturated solution obtained in step (2), control the mass ratio of abrasive to sodium chloride solute to be 0.25:1, disperse it ultrasonically with a power of 60w, and simultaneously stir it mechanically at 200r / min for 2min. Then, under the heating condition of 90℃, stir at 400r / min until the solution is completely evaporated to obtain the core-shell abrasive semi-finished product.

[0131] (4) Place the semi-finished core-shell abrasive obtained in step (3) in a drying oven at 60°C for 1 hour, grind the dried core-shell abrasive with a mortar and pestle, and then sieve it with a 400-mesh sieve to obtain a uniformly dispersed water-soluble core-shell abrasive.

[0132] The overall structure of the water-soluble core-shell abrasive polishing disc is as follows: Figure 2 As shown, the polishing disc includes a core-shell abrasive with a water-soluble outer shell and a polishing disc substrate, wherein the polishing disc substrate is polyurethane-based. The preparation method of the water-soluble core-shell abrasive polishing disc is the same as in Example 10.

[0133] Example 14

[0134] The difference from Example 13 is that the diamond abrasive particle size in step (3) of this example is 1 μm, while the other steps are the same.

[0135] Example 15

[0136] The difference from Example 13 is that the diamond abrasive particle size in step (3) of this example is 3μm, while the other steps are the same.

[0137] Example 16

[0138] The difference from Example 10 is that the outer layer of the water-soluble inorganic salt is barium chloride.

[0139] The core-shell abrasive with a water-soluble outer shell consists of an inner abrasive layer and an outer water-soluble inorganic salt layer. Both the core-shell abrasive and the inner abrasive layer are granular. The average particle size of the core-shell abrasive is 9 μm, the average particle size of the inner abrasive layer is 5 μm, and the average thickness of the outer water-soluble inorganic salt layer is 2 μm. The outer water-soluble inorganic salt layer is barium chloride, and the inner abrasive layer is diamond.

[0140] like Figure 1 As shown, the method for preparing a water-soluble core-shell abrasive includes the following steps:

[0141] (1) At 25°C, deionized water and surfactant sodium dodecyl sulfate were added to a polytetrafluoroethylene beaker and mixed. The mass ratio of deionized water to surfactant was 10000:1. The mixture was ultrasonically dispersed at a power of 60W and simultaneously mechanically stirred at 200r / min for 1min until the surfactant was completely dissolved, thus obtaining an aqueous solution of surfactant.

[0142] (2) The surfactant aqueous solution obtained in step (1) and the water-soluble inorganic salt barium chloride are mixed at a mass ratio of 100:36, ultrasonically dispersed at a power of 60w, and simultaneously mechanically stirred at 200r / min for 2min until all the water-soluble inorganic salt is dissolved to obtain a saturated solution of water-soluble inorganic salt.

[0143] (3) Mix the diamond abrasive with a particle size of 5μm with the water-soluble inorganic salt saturated solution obtained in step (2), control the mass ratio of abrasive to barium chloride solute to be 0.25:1, disperse it ultrasonically with a power of 60w, and simultaneously stir it mechanically at 200r / min for 2min. Then, under the heating condition of 90℃, stir it at 400r / min until the solution is completely evaporated to obtain the core-shell abrasive semi-finished product.

[0144] (4) Place the semi-finished core-shell abrasive obtained in step (3) in a drying oven at 60°C for 1 hour, grind the dried core-shell abrasive with a mortar and pestle, and then sieve it with a 400-mesh sieve to obtain a uniformly dispersed water-soluble core-shell abrasive.

[0145] The overall structure of the water-soluble core-shell abrasive polishing disc is as follows: Figure 2 As shown, the polishing disc includes a core-shell abrasive with a water-soluble outer shell and a polishing disc substrate, wherein the polishing disc substrate is polyurethane-based. The preparation method of the water-soluble core-shell abrasive polishing disc is the same as in Example 10.

[0146] Example 17

[0147] The difference from Example 16 is that the diamond abrasive particle size in step (3) of this example is 1 μm, while the other steps are the same.

[0148] Example 18

[0149] The difference from Example 16 is that the diamond abrasive particle size in step (3) of this example is 3μm, while the other steps are the same.

[0150] Comparative Example 2

[0151] The method for preparing a polishing disc includes the following steps:

[0152] 1) Weigh the raw materials according to the following mass percentages: diamond abrasive 10%, polyurethane prepolymer 70%, hydroxypropyl silicone oil 18%, stannous octoate 0.001%, chain extender MOCA 1.9%;

[0153] Diamond abrasive, polyurethane prepolymer, hydroxypropyl silicone oil and stannous octoate were mixed and ultrasonically stirred at 600 r / min for 20 min at 70 °C. Then, chain extender MOCA was added and the stirring speed was increased to 1000 r / min for 30 s to obtain a mixture. The mixture was injected into a mold coated with polytetrafluoroethylene and a pressure of 2 kg was applied. The mixture was allowed to stand and cure at 115 °C for 16 h.

[0154] 2) Use a grinding wheel to finish the surface of the semi-finished polishing disc obtained in step 1) to ensure that the surface of the polishing disc has a high flatness of ±0.01mm, and thus obtain the polishing disc.

[0155] Polishing test

[0156] A 2-inch 4H-SiC wafer processing experiment was conducted on a KD15BX single-sided grinding machine using the polishing pads of Examples 1-18 and Comparative Examples 1-2. The 4H-SiC wafers were manufactured by Beijing Tianke Heda Blue Light Semiconductor Co., Ltd., with an initial surface roughness of 10±0.3nm. The polishing pressure was 80kPa, the rotation speed was 60r / min, the added polishing fluid was deionized water, the drop rate was 2.5mL / min, and the processing time was 60min. Figure 3 This is a schematic diagram of the polishing process.

[0157] The surface morphology and surface roughness of the polished 4H-SiC wafers were inspected using a white light interferometer. The material removal rate was calculated by weighing the mass change of the workpiece before and after polishing using a precision electronic balance (accuracy of 0.1 mg). The polishing test results of the polishing discs of Examples 1-18 and Comparative Examples 1-2 on the 4H-SiC wafers are shown in Table 3.

[0158] Table 3 shows the results of polishing 4H-SiC wafers using polishing pads in Examples 1-18 and Comparative Examples 1-2.

[0159] Material removal rate (nm / min) Surface roughness Ra (nm) Example 1 8.43 0.752 Example 2 5.52 0.647 Example 3 6.94 0.685 Example 4 8.35 0.752 Example 5 5.62 0.647 Example 6 6.73 0.685 Example 7 8.64 0.752 Example 8 5.44 0.647 Example 9 7.07 0.685 Example 10 6.86 0.336 Example 11 3.48 0.287 Example 12 4.74 0.318 Example 13 6.86 0.343 Example 14 3.48 0.296 Example 15 4.74 0.321 Example 16 6.86 0.325 Example 17 3.48 0.272 Example 18 4.74 0.311 Comparative Example 1 17.32 2.134 Comparative Example 2 10.28 1.537

[0160] Based on the polishing results of the 4H-SiC wafers prepared by the polishing pads in Examples 1-18 and Comparative Examples 1-2 in Table 2, it can be seen that:

[0161] Compared to patent CN 118438342 A, the material removal rate and surface roughness of epoxy resin-based and polyurethane-based polishing pads were reduced after polishing, indicating that the water-soluble shell polishing pads can reduce surface / subsurface damage and improve surface quality.

[0162] Compared to epoxy resin-based polishing pads, polyurethane-based polishing pads result in lower material removal rates and reduced surface roughness after polishing. This is because polyurethane is a soft matrix, while epoxy resin is a hard matrix. Soft matrices have better flexibility, which reduces the removal rate but increases the surface roughness.

[0163] Polishing discs with different water-soluble shell abrasives show little difference in material removal rate and surface roughness after polishing.

[0164] Polishing discs made from large-particle-size core-shell abrasives exhibit high material removal rates and high surface roughness, while polishing discs made from small-particle-size core-shell abrasives show low material removal rates but low surface roughness. This is because after the core-shell abrasives dissolve into free abrasive particles, the small-particle abrasives achieve low roughness through shallow cutting, close contact, and plastic removal, but remove less material per unit time. In contrast, the large-particle abrasives achieve high removal rates through deep cutting, sparse contact, and brittle fracture, but suffer more severe surface damage.

[0165] In Examples 1 and 9 and Comparative Examples 1 and 2, after the outer layer of the core-shell abrasive is dissolved, the polishing disk can enable the wafer to obtain a lower surface roughness.

[0166] The description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A core-shell abrasive with a water-soluble outer shell, characterized in that, It consists of an inner abrasive layer and an outer layer of water-soluble inorganic salt. Both the core-shell abrasive and the inner abrasive layer are granular. The average particle size of the core-shell abrasive is 0.2-12 μm, the average particle size of the inner abrasive layer is 0.1-10 μm, and the average thickness of the outer layer of water-soluble inorganic salt is 0.05-2 μm. The outer layer of the water-soluble inorganic salt includes one or more of sodium chloride, sodium sulfate, or barium chloride.

2. The core-shell abrasive with a water-soluble outer shell according to claim 1, characterized in that, The inner layer of the abrasive includes one or more of diamond, alumina, cerium oxide, silicon dioxide, or silicon carbide.

3. A method for preparing a core-shell abrasive with a water-soluble outer shell as described in claim 1 or 2, characterized in that, The steps include the following: (1) At 20-30℃, deionized water and surfactant are mixed with a mass ratio of (500-10000):

1. The mixture is ultrasonically dispersed with a power of 60w and simultaneously mechanically stirred at 200r / min for 1-2min until the surfactant is completely dissolved to obtain an aqueous solution of surfactant. (2) The surfactant aqueous solution and water-soluble inorganic salt obtained in step (1) are mixed in a mass ratio of (71-84):(16-29), ultrasonically dispersed at a power of 60w, and simultaneously mechanically stirred at 200r / min for 1-2min until all water-soluble inorganic salt is dissolved to obtain a saturated solution of water-soluble inorganic salt. (3) Mix the abrasive with the saturated solution of water-soluble inorganic salt obtained in step (2), and control the mass ratio of abrasive to water-soluble inorganic salt to solute to be (0.125-1):

1. Disperse the mixture with ultrasonic power of 60W and simultaneously stir mechanically at 200r / min for 1-2min. Then, under the heating condition of 70-110℃, stir at 200-600r / min until the solution is completely evaporated to obtain the core-shell abrasive semi-finished product. (4) Place the core-shell abrasive semi-finished product obtained in step (3) in a drying oven at 60-80℃ for 1-2 hours, grind the dried core-shell abrasive, and then sieve it through a 200-1000 mesh screen to obtain a uniformly dispersed water-soluble core-shell abrasive.

4. The method for preparing a water-soluble core-shell abrasive according to claim 3, characterized in that, In step (1), the surfactant includes any one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or polyethylene glycol.

5. A water-soluble core-shell abrasive polishing disc, characterized in that, The core-shell abrasive with a water-soluble shell as described in claim 1 or 2, or the core-shell abrasive with a water-soluble shell prepared by the method described in any one of claims 3-4, and the polishing disc substrate.

6. The core-shell abrasive polishing disc with a water-soluble outer shell according to claim 5, characterized in that, The polishing disc substrate includes epoxy resin-based or polyurethane-based materials.

7. A method for preparing a core-shell abrasive polishing disc with a water-soluble outer shell as described in claim 5 or 6, characterized in that, The steps include the following: 1) Mix the water-soluble core-shell abrasive with the polishing disc substrate to obtain a mixture. The mass percentage of the water-soluble core-shell abrasive in the mixture is 5-10%. Pour the mixture into the polishing disc mold and solidify it to obtain a semi-finished polishing disc. 2) The surface of the semi-finished polishing disc obtained in step 1) is finished with a grinding wheel to ensure that the surface of the polishing disc has a flatness of ±0.01mm, thus obtaining the water-soluble shell core-shell abrasive polishing disc.

8. The method for preparing a core-shell abrasive polishing disc with a water-soluble outer shell according to claim 7, characterized in that, When the polishing pad substrate is epoxy resin based, step 1) is as follows: Weigh each raw material according to the following mass percentages: 5-10% for water-soluble core-shell abrasive, 70-74% for epoxy resin, and 20-21% for curing agent; Mix the water-soluble core-shell abrasive with epoxy resin and stir at 1000-1200 r / min for 30-60 min. Then add the curing agent and stir at 1000-1200 r / min for 5-10 min to obtain a mixture. Pour the mixture into a polishing disc mold and let it stand and cure at 23-26℃ for 10-12 h. The curing agent includes any one of T31, ethylenediamine, cyclohexylamine, or polyamide ester.

9. The method for preparing a core-shell abrasive polishing disc with a water-soluble outer shell according to claim 7, characterized in that, When the polishing pad substrate is polyurethane-based, step 1) is as follows: Weigh each raw material according to the following mass percentages: 5-10% water-soluble core-shell abrasive, 65-75% polyurethane prepolymer, 20-25% hydroxypropyl silicone oil, 0.001% stannous octoate, and 1-2% chain extender MOCA. Water-soluble core-shell abrasive, polyurethane prepolymer, hydroxypropyl silicone oil and stannous octoate are mixed and ultrasonically dispersed at 60W at 70-80℃, while stirring at 500-600r / min for 20min. Then, chain extender MOCA is added, and the stirring speed is increased to 1000-1200r / min for 30s to obtain a mixture. The mixture is injected into a polytetrafluoroethylene-coated mold and a pressure of 2kg is applied. The mixture is then allowed to stand and cure at 115℃ for 16h.

10. The application of a core-shell abrasive polishing disc with a water-soluble shell as described in any one of claims 5-6 or a core-shell abrasive polishing disc with a water-soluble shell prepared by the method described in any one of claims 7-9 in workpiece polishing.

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