A bonding agent and ultrafine diamond grinding wheel prepared using the same

Abstract

The present invention relates to a bonding agent comprising the following raw materials in percentage by weight: 25-50% thermosetting epoxy resin powder, 5-10% short fibers, 20-40% thermoplastic elastomer, 5-25% aerogel powder, and 2%-15% foaming agent. The present invention also provides an ultrafine diamond grinding wheel containing the bonding agent, which is prepared by mixing the bonding agent and diamond in a mass ratio of 3:7-5:5. The ultrafine diamond grinding wheel can meet the high finish requirements of existing semiconductor wafer materials and ultra-thin liquid crystal glass panel materials, and can meet high surface quality and high precision processing requirements.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic abrasive tool manufacturing, and specifically relates to a soft and tough bond, its preparation, and an ultrafine diamond grinding wheel abrasive tool prepared using the same, which can be used for high-finish processing of wafer materials in the semiconductor industry, ultra-thin liquid crystal glass panel materials in the liquid crystal display industry, and the like. Background Art

[0002] Silicon, gallium arsenide, gallium nitride, and silicon carbide are key materials for semiconductor chips, primarily used in integrated circuits, discrete devices, sensors, and other fields. The surface quality of wafers directly impacts the yield and performance of subsequent chips. Their flatness and smoothness are generally controlled within 50nm, primarily achieved through precision processes such as grinding, chamfering, and polishing.

[0003] Ultra-thin liquid crystal glass is used in displays and internal screens for various computers, mobile phones, televisions, and the electronic machinery industry. Its thickness generally ranges from 0.2mm to 0.5mm, and its planar length and width can reach over 1000mm. Float glass is a commonly used glass production technology. The glass panels produced undergo various processing techniques, including lamination, cutting, cleaning, and beveling, to produce consumer electronic internal screens with certain optical and electrical properties. The glass panels require chamfering and fine grinding on all four sides to remove any chips and burrs on the edges of the panel, resulting in a bright and smooth surface. This ensures that the glass panel will not break, chip, or fragment at the corners due to chipping defects during subsequent processing, thereby improving the overall panel utilization rate.

[0004] Ultra-precision grinding, edge polishing, chamfer grinding, and polishing of the above materials are processed using diamond grinding wheels prepared with existing hard and brittle binder systems such as phenolic resin or polyimide resin. These wheels are prone to problems such as chipping, low grinding efficiency, heavy load on supporting equipment, and occasional scratches on the surface. Therefore, diamond grinding wheels with soft elasticity and high toughness are needed for high-smoothness and high-surface-quality processing to meet their high surface quality and high-precision requirements. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a soft flexible binder and an ultrafine diamond grinding wheel prepared therefrom to meet the high finish, high surface quality and high precision processing requirements of existing semiconductor wafer materials and ultra-thin liquid crystal glass panel materials.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A soft, flexible binder comprises the following raw materials in percentage by weight: 25-50% thermosetting epoxy resin powder, 5-10% short fibers, 20-40% thermoplastic elastomer, 5-25% aerogel powder, and 2-15% foaming agent. The soft, flexible binder is obtained by uniformly mixing the raw materials in the appropriate proportions.

[0008] Specifically, the melting point of the thermosetting epoxy resin powder is in the range of 50-100° C., and the ICI viscosity is less than 1.

[0009] Specifically, the short fibers are selected from one or a mixture of two or more of polypropylene fibers, polyurethane fibers, carbon fibers, calcium silicate fibers, basalt fibers, etc.; the diameter of the short fibers is 5-50 μm, and the length is 50-200 μm.

[0010] Furthermore, the thermoplastic elastomer is one or a mixture of two or more of styrene rubber, vinyl chloride rubber, polyurethane rubber, etc.; the particle size of the thermoplastic elastomer is in the range of 20-100 μm.

[0011] Specifically, the aerogel powder is a silica aerogel powder with a nano-void structure, a thermal conductivity of less than 0.018 W / m·K at room temperature, and a porosity of more than 90%.

[0012] Furthermore, the foaming agent is EVA foaming agent and / or NC foaming agent; and the foaming temperature is 70-100°C.

[0013] The raw materials of the soft flexible binder of the present invention are composed of five raw materials, namely thermosetting epoxy resin powder, short fibers, thermoplastic elastomer, aerogel powder, and foaming agent. In this formula, the five raw materials play their respective roles, as follows.

[0014] Thermosetting epoxy resin powder has excellent bonding properties, superior water resistance compared to other phenolic resins, and low viscosity. In this invention, it is used as a binder, combined with other materials to form a bonding and polishing bond to bond diamond abrasives for grinding and polishing semiconductor wafers. Its performance requirements include: 1) a melting point range of 50-100°C; 2) an ICI viscosity (Poise / 150°C) of less than 1. The thermosetting epoxy resin used in this invention is SQE-104, produced by Jinan Shengquan Group Co., Ltd.

[0015] The short fibers in the present invention have a reinforcing and toughening effect. In particular, given that the mechanical strength of the thermosetting epoxy resin in the present invention is lower than that of the phenolic resin and polyimide resin commonly used in the manufacture of superhard abrasive tools, the short fibers provide a reinforcing and toughening effect, increasing the strength and toughness of the binder prepared by the present invention. Furthermore, the short fibers provide a certain degree of elasticity, enabling full-encapsulation grinding of semiconductor wafer corners without brittle fracture of the diamond layer or the binder layer. The short fibers have the following performance requirements: a diameter of 5-50 μm and a length of 50-200 μm. They can be organic fibers, such as polypropylene fibers, polyurethane fibers, and carbon fibers, or inorganic fibers, such as calcium silicate fibers and basalt fibers.

[0016] The thermoplastic elastomer can be one or more of styrene rubber, vinyl chloride rubber, or polyurethane rubber (TPU). As unit blocks, the thermoplastic elastomer is uniformly dispersed in the binder structure as macromolecules. Its role in the present invention is to increase the elasticity of the binder system, reduce its brittleness, prevent brittle fracture during grinding, and improve its impact resistance. Furthermore, abrasive tools (grinding wheels) made with this binder exhibit excellent wear and impact resistance, good polishing properties, and a larger contact area with irregularly shaped surfaces during grinding, providing wider coverage and high grinding efficiency. Performance requirements include a particle size range of 20-100 μm, which can be crushed by ball milling before use.

[0017] Aerogel powder is a silica (SiO2) aerogel powder with a nanoporous structure. This material features extremely high porosity, very low density, high specific surface area, and ultra-high pore volume. In the present invention, it is primarily utilized for two purposes: First, its extremely high thermal insulation properties. Because grinding wheels prepared with this binder generate significant heat during grinding and polishing, the grinding contact surface temperature can exceed 200°C. While the thermosetting epoxy resin used in this invention is more flexible than phenolic and polyimide resins, it lacks the heat resistance of commonly used phenolic and polyimide resins. The addition of aerogel powder provides excellent thermal insulation, preventing the bond and the grinding wheel from heating up and causing ablation during grinding. Second, this material has an extremely low density. Its application in the present invention can reduce the density of the bond and the grinding wheel, improving the wheel's resistance to grinding heat, making the wheel's internal structure more fluffy, increasing its impact toughness, and enhancing its ability to wrap around the material during grinding. Therefore, this material plays a crucial role in this invention. Its performance requirements are: 1) thermal conductivity less than 0.018 W / m·K at room temperature (25°C); 2) porosity greater than 90%, with the higher the porosity, the better the thermal insulation effect; and 3) particle size within 10-30 μm.

[0018] The foaming agent is an environmentally friendly EVA powder foaming agent and / or an NC foaming agent (a commonly available commercial product, consisting of a mixture of baking soda and other catalysts). The foaming agent in this invention forms micropores in the binder, increasing its chip-holding capacity. It also creates internal bulk, reducing its structural density, increasing its toughness, and reducing its rigidity, resulting in flexible grinding rather than rigid grinding when grinding or polishing wafers. Flexible grinding significantly improves the surface quality of the ground material, avoids scratches, and reduces surface roughness, achieving a mirror-like or even brighter finish. Performance requirements: The foaming temperature must be between 70-100°C to meet the requirements for subsequent water-bath hot-melt forming. The foaming agent in this invention can be either environmentally friendly EVA foaming agent powder or NC foaming agent, or both. The JN200 foaming agent from Qingdao Gabet New Material Technology Co., Ltd. is used.

[0019] The invention provides an ultrafine diamond grinding wheel containing the bonding agent. The bonding agent and diamond are mixed in a mass ratio of 3:7-5:5 to prepare the ultrafine diamond grinding wheel.

[0020] Furthermore, the diamond is ultrafine diamond, preferably ultrafine diamond with a particle size of 400#-15000#, and the diamond type can be polycrystalline diamond powder and / or single crystal diamond powder, etc.

[0021] The present invention also provides a preparation method of the ultrafine diamond grinding wheel, which includes mixing, water bath hot melt molding, hot air curing, and cold environment shrinkage toughening. The specific steps are as follows:

[0022] 1) Mixing: Take the raw materials of the binder and diamond according to the proportion, mix them in a three-dimensional mixer for 0.5-2 hours, take them out and set aside;

[0023] 2) Waterbath hot melt molding: Place the powder molding material mixed in step 1) into the mold cavity, cover the mold head, and ensure that the bottom of the mold head is 5-10mm above the molding material layer. Under waterproof and sealed conditions (place the mold in a PTFE waterproof sealing device), place it in a water bath container. The water bath temperature is set to a fixed temperature of 70-100°C depending on the formula and mold size. The water bath hot melt molding time is 80-240 minutes. At this time, the molding material inside the mold will slowly melt and solidify under the water bath temperature, filling the mold cavity and forming the required grinding wheel. After the molding time is up, remove the mold, unmold it, and proceed to the next step;

[0024] 3) Hot air curing: The diamond grinding wheel ring formed in step 2) is hot-air cured. The purpose of hot air curing is to fully stretch the molecular chain of the bond, reduce the existence of internal stress, increase its flexibility, increase the degree of curing of the epoxy resin, and slowly release the foaming small molecules, making the bond and the internal structure of the grinding wheel more uniform. After the grinding wheel is hot-air cured, it enters the next manufacturing process.

[0025] 4) Cold environment shrinkage and toughening: Place the diamond grinding wheel ring that has been hot-air cured in step 3) in a -10 ~ 0°C environment for shrinkage and toughening, let it stand for 1-3 hours, and then remove it. Because the formula structure contains aerogel and foaming agent powder, it will expand significantly after thermoforming and heat curing, resulting in an excessive expansion ratio of the binder and increased brittleness. This is prone to brittle tempering when grinding the wafer material. To prevent this phenomenon, a cold environment process is required to allow the excessively collided structure to naturally shrink and achieve the most stable structure. Specifically, depending on the size and density of the abrasive (grinding wheel), it can be placed in a freezer or other cold atmosphere device, with the temperature controlled at -10 ~ 0°C and the standing time for 1-3 hours.

[0026] 5) The diamond grinding wheel ring toughened by cold shrinkage in step 4) is bonded to a substrate and processed conventionally to obtain an ultra-fine-grained diamond grinding wheel.

[0027] Furthermore, the hot air curing in step 3) is carried out in a hot air circulation oven, and the specific temperature-time curve process parameters of the oven are as follows: 30°C for 15 minutes, 45°C for 20 minutes, 55°C for 20 minutes, 60°C for 20 minutes, 65°C for 15 minutes, 70°C for 15 minutes, and 80°C for 200 minutes.

[0028] The core of the technical solution of the present invention is divided into two parts. The first is the design of the raw material ratio. The second is that it is different from the hot pressing and sintering molding in the existing superhard material industry. It uses a brand-new multi-phase solid-liquid water bath hot melt molding, hot air drying and curing, and cold environment shrinkage and exhaust toughening process technology for preparation. The biggest difference between the binder of the present invention and the diamond grinding wheel prepared is that it has toughness and soft elasticity, which is completely different from the hard and brittle processing of ordinary resin grinding wheels. Compared with the existing technology, the beneficial effects of the present invention are as follows:

[0029] 1) The binder of the present invention has a hardness of HR15N < 18, which is much lower than the binders prepared from commonly used phenolic resins and polyimide resins. Conventional manual pressing can produce a depression, and it has good flexibility and low hardness; the elastic modulus is not greater than 105 N / m 2 , with good elasticity;

[0030] 2) The ultrafine diamond grinding wheel of the present invention has excellent flexibility, toughness, and the ability to wrap around the narrow edges or narrow angles of the processed material. It can fully cover the edges of wafers and ultra-thin glass, fully grind, and polish flexibly. It has a certain rebound effect and can be used for ultra-precision grinding without causing brittle burns or scratches. It also has small or no chipping and a smooth surface. The surface finish after processing is Ra <0.015μm.

[0031] 3) The soft and tough bond produced by the present invention, and the ultrafine diamond grinding wheel prepared with this bond, possess a soft and tough property not possessed by conventional ultrahard abrasive tools made from resins such as phenolic resin and polyimide resin. Firstly, the five raw materials in the present invention's bond are innovative and unique, and are all used for the first time in the manufacture of ultrahard diamond grinding wheels. Secondly, the water-bath hot-melt molding process and cold-environment shrinkage toughening process adopted by the present invention are both innovative and first-time applications in the industry, with unique functional characteristics. This ultrafine diamond grinding wheel can meet the high finish, high surface quality, and high precision processing requirements of existing semiconductor wafer materials and ultra-thin liquid crystal glass panel materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 An ultrafine diamond grinding wheel prepared with binder A in Example 1 of the present invention;

[0033] Figure 2 An ultrafine diamond grinding wheel prepared with binder B according to Example 2 of the present invention;

[0034] Figure 3 An ultrafine diamond grinding wheel prepared with binder C according to Example 3 of the present invention;

[0035] Figure 4 The processing effect of ultra-thin liquid crystal glass after using the ultra-fine diamond grinding wheel prepared with binder C in Example 3 of the present invention;

[0036] Figure 5 Comparison diagram of the internal structure of diamond grinding wheels prepared using the binders of Example 2 (left) and Comparative Example 2 (right);

[0037] Figure 6 This is the processing effect of the diamond grinding wheel prepared with the binder of Comparative Example 3 after processing the ultra-thin liquid crystal glass; Figure 6 The position indicated by the middle circle shows: severe chipping, poor finish and poor grinding effect. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0039] In the following examples, unless otherwise specified, all raw materials used are common commercial products available in the art.

[0040] The thermosetting epoxy resin powder used has a melting point of 50-100°C and an ICI viscosity of less than 1 (Jinan Shengquan Group Co., Ltd.). The short fibers have a diameter of 5-50 μm and a length of 50-200 μm. The thermoplastic elastomer has a particle size of 20-100 μm. The aerogel powder is a silica aerogel powder with a nanoporous structure (purchased from Shenzhen Zhongning Technology Co., Ltd.). Its thermal conductivity at room temperature is less than 0.018 W / m·K and its porosity is greater than 90%. The foaming agent used has a foaming temperature of 70-100°C (Qingdao Gabet New Material Technology Co., Ltd.).

[0041] Example 1: Preparation of a soft and flexible binder A and a diamond grinding wheel with a particle size of 400# for chamfering silicon carbide wafers prepared from the binder A.

[0042] A soft flexible binder A comprises the following raw materials in percentage by mass: 37% thermosetting epoxy resin powder, 10% short fiber carbon fiber, 30% thermoplastic elastomer vinyl chloride rubber, 15% aerogel powder, and 8% EVA foaming agent.

[0043] The preparation method of the ultrafine diamond grinding wheel comprises the following steps:

[0044] 1) Mixing: Take the raw materials of the binder and diamond (single crystal diamond, particle size 400#) in proportion, accurately weigh the binder and diamond in a mass ratio of 3:7, and control the accuracy within ±0.1g; after stirring, place in a three-dimensional mixer and mix for 0.5 hours, remove and set aside;

[0045] 2) Waterbath hot melt molding: Place the powder molding material mixed in step 1) into a mold cavity shaped like 1A8-203mm×7.5mm×20mm. Cover the mold with the mold pressure head, ensuring that the bottom of the mold pressure head is 5mm above the molding material layer. Place the mold in a PTFE waterproof sealing device (to ensure waterproof sealing conditions). Place the device in a water bath container, set the water bath temperature to 70°C, and the water bath hot melt molding time for 80 minutes. Allow the molding material to slowly melt and solidify inside, filling the mold cavity and forming the required grinding wheel. After the molding time is up, remove the mold, unmold it, and proceed to the next step;

[0046] 3) Hot air curing: The 1A8-203mm×7.5mm×20mm diamond grinding wheel ring obtained in step 2) was placed in a hot air oven for hot air curing. The specific oven temperature and time curve parameters were as follows: 30°C for 15 minutes, 45°C for 20 minutes, 55°C for 20 minutes, 60°C for 20 minutes, 65°C for 15 minutes, 70°C for 15 minutes, and 80°C for 200 minutes.

[0047] 4) Cold environment shrinkage toughening: Place the diamond grinding wheel ring that has been hot-air cured in step 3) in an environment of -7 to -8°C for 1 hour, then take it out; then bond it to the substrate and undergo conventional processing to obtain an ultra-fine diamond grinding wheel (such as Figure 1 The grinding wheel structure is conventional in the art and not a novel feature of this application, so it will not be described in detail here. The same applies hereinafter. It can be used for ultra-precision chamfering of silicon carbide wafers. Table 1 below shows the process and processing results of the ultra-fine diamond used in this invention for silicon carbide wafer processing.

[0048] Table 1 Technical parameters and effects applied to 4-6 inch silicon carbide wafer processing

[0049]

[0050] The results in Table 1 show that the ultrafine diamond of the present invention is used for chamfering of 4-6 inch silicon carbide wafers, and the chamfers have no chipping, a smooth surface, and a surface finish Ra of 0.01-0.015 μm.

[0051] Example 2: Preparation of a soft and flexible binder B and a grinding wheel with a particle size of 2000# for fine grinding and chamfering of silicon wafers prepared from the binder B.

[0052] A soft and flexible binder B comprises the following raw materials in percentage by mass: 25% thermosetting epoxy resin powder, 8% short fiber polyurethane fiber, 40% thermoplastic elastomer polyurethane rubber TPU, 25% aerogel powder, and 2% EVA foaming agent.

[0053] The preparation method of the ultrafine diamond grinding wheel comprises the following steps:

[0054] 1) Mixing: Take the raw materials of the binder and diamond (single crystal diamond, particle size 2000#) in proportion, accurately weigh the binder and diamond in a mass ratio of 4:6, and control the accuracy within ±0.1g; after stirring, place in a three-dimensional mixer and mix for 1 hour, remove and set aside;

[0055] 2) Waterbath hot melt molding: Place the powder molding material mixed in step 1) into a mold cavity shaped like 1A8-101mm×21mm×80mm. Cover the mold with the mold pressure head, ensuring that the bottom of the mold pressure head is 8mm above the molding material layer. Place the mold in a PTFE waterproof sealing device (to ensure waterproof sealing conditions). Place the device in a water bath container, set the water bath temperature to 80°C, and heat the water bath for 120 minutes. Allow the molding material to slowly melt and solidify, filling the mold cavity and forming the required grinding wheel. After the molding time is up, remove the mold, unmold it, and proceed to the next step.

[0056] 3) Hot air curing: The 1A8-101mm×21mm×80mm diamond grinding wheel ring obtained in step 2) was placed in a hot air oven for hot air curing. The specific oven temperature and time curve parameters were as follows: 30°C for 15 minutes, 45°C for 20 minutes, 55°C for 20 minutes, 60°C for 20 minutes, 65°C for 15 minutes, 70°C for 15 minutes, and 80°C for 200 minutes.

[0057] 4) Cold environment shrinkage toughening: Place the diamond grinding wheel ring that has been hot-air cured in step 3) in an environment of -5 to -6°C for 1.2 hours, then take it out; then bond it to the substrate and undergo conventional processing to obtain an ultra-fine diamond grinding wheel (such as Figure 2 (as shown in Figure 2) can be used for ultra-precision chamfering of silicon wafers. Specific processing data is shown in Table 2 below.

[0058] Figure 5 The internal structure diagram of the ultrafine diamond grinding wheel prepared in Example 2 is given. Figure 5 The results show that there are voids inside the prepared ultrafine diamond grinding wheel, and the voids are evenly distributed.

[0059] Table 2 Technical parameters and effects of 8-inch silicon wafer beveling processing

[0060]

[0061] The results in Table 2 show that the ultrafine diamond of the present invention is used for chamfering of 8-inch silicon wafers, and the chamfers have no chipping, a smooth surface, and a surface finish Ra of 0.005-0.01 μm.

[0062] Example 3: Preparation of a soft and flexible binder C and a grinding wheel with a particle size of 8000# prepared from the binder C for chamfering ultra-thin liquid crystal glass.

[0063] A soft flexible binder B comprises the following raw materials in percentage by mass: 50% thermosetting epoxy resin powder, 8% short fiber calcium silicate fiber, 22% thermoplastic elastomer styrene rubber, 12% aerogel powder, and 8% NC foaming agent.

[0064] The preparation method of the ultrafine diamond grinding wheel comprises the following steps:

[0065] 1) Mixing: Take the raw materials of the binder and diamond (single crystal diamond, particle size 2000#) in proportion, accurately weigh the binder and diamond in a mass ratio of 5:5, and control the accuracy within ±0.1g; after stirring, place in a three-dimensional mixer and mix for 1 hour, remove and set aside;

[0066] 2) Waterbath hot melt molding: Place the powder molding material mixed in step 1) into a mold cavity with a shape of 1A8-101mm (mold cavity outer diameter) × 10mm (mold cavity height) × 82mm (mold cavity inner diameter) and a shape of 89mm (mold cavity outer diameter) × 10mm (mold cavity height) × 80mm (mold cavity inner diameter). Cover the mold with the mold pressure head, so that the bottom of the mold pressure head is 6mm above the molding material layer. Place the mold in a PTFE waterproof sealing device (to ensure waterproof sealing conditions), place the device in a water bath container, set the water bath temperature to 90°C, and water bath hot melt molding time for 160 minutes. Allow the molding material to slowly melt and solidify inside, filling the mold cavity and forming the required grinding wheel tool. After the molding time is up, remove the mold, unmold it, and proceed to the next step;

[0067] 3) Hot air curing: The 1A8-101 mm × 10 mm × 82 mm and 89 mm × 10 mm × 80 mm diamond grinding wheel rings obtained in step 2) were placed in a hot air oven for hot air curing. The specific oven temperature and time curve parameters were as follows: 30°C for 15 minutes, 45°C for 20 minutes, 55°C for 20 minutes, 60°C for 20 minutes, 65°C for 15 minutes, 70°C for 15 minutes, and 80°C for 200 minutes.

[0068] 4) Cold environment shrinkage toughening: Place the diamond grinding wheel ring that has been hot-air cured in step 3) in an environment of -4 to -5°C for 1.5 hours, then take it out; then bond it to the substrate and undergo conventional processing to obtain an ultra-fine diamond grinding wheel (such as Figure 3 As shown), it can be used for ultra-precision chamfering of ultra-thin liquid crystal glass.

[0069] The ultrafine diamond grinding wheel prepared in this example is used for ultra-precision chamfering of ultra-thin liquid crystal glass, and the liquid crystal glass with a thickness of 0.25-0.5 mm is processed. The specific processing data are shown in Table 3 below, and the processing effect is shown in Figure 4 .

[0070] Table 3 Technical parameters and effects of ultra-thin liquid crystal glass processing

[0071]

[0072] The test results show that within 30,000 meters, the glass edge is magnified 100 times and the chipping is less than 0.01 micron; the grinding wheel life is 2 million meters; and the surface finish Ra is less than 0.015μm. Figure 4 The results showed that no cracks were observed under a 100x magnifying glass.

[0073] Comparative Example 1

[0074] The difference from Example 1 is that the thermosetting epoxy resin powder is replaced by thermosetting phenolic resin or polyimide resin powder in the bonding agent. The preparation method of the diamond grinding wheel is similar to that of Example 1.

[0075] The binder hardness HR15N of this comparative example 1 is much greater than 18. After experimental testing, the binder hardness HR15N is between 50-80. Such a high hardness shows high hardness and high brittleness. The diamond grinding wheel prepared with this high hardness and high brittleness binder cannot show its flexibility at all, so when grinding the edge of the silicon carbide wafer, flexible coverage cannot be achieved. Only a part of the grinding layer contacts the silicon carbide wafer, which results in the inability to fully cover the part of the silicon carbide wafer and achieve ultra-precision grinding effect. Moreover, the diamond grinding wheel prepared with such a high hardness binder is a hard-on-hard grinding of such a high silicon carbide crystal, which will cause burns, scratches and other phenomena.

[0076] Therefore, other systems that are separated from the binder formula system of the present invention cannot achieve the corresponding grinding effect, are prone to burns and scratches, cannot fully cover the workpiece during grinding, and have poor grinding effects.

[0077] Comparative Example 2

[0078] The difference from Example 2 is that aerogel powder is omitted from the binder formula. The preparation method of the diamond grinding wheel refers to Example 2.

[0079] The binder formed by the formula of this comparative example 2 does not have a porous structure. The internal structure of the diamond grinding wheel prepared is shown in FIG. Figure 5 , Figure 5 The results show that the diamond grinding wheel has no internal voids. Diamond grinding wheels made with this bond cannot achieve high self-sharpening performance, lack space to accommodate grinding debris, and cannot achieve high-precision grinding. The surface finish of silicon wafers ground is poor and chipping is severe. The results of the tests on silicon wafer grinding are shown in Table 4 below.

[0080] Table 4 Effect of diamond grinding wheel prepared in comparative example 2 on grinding silicon wafer

[0081]

[0082] The results in Table 4 show that when the diamond grinding wheel in Comparative Example 2 is used for chamfering of 8-inch silicon carbide wafers, the chamfer chipping is greater than 50 μm and the surface finish Ra is greater than 0.5 μm, which does not meet the requirements of ultra-precision grinding at all.

[0083] Comparative Example 3

[0084] The difference from Example 3 is that the grinding wheel is prepared using a conventional mold hot pressing process (e.g., setting the temperature on the press to 150-230°C, fixed mold forming or fixed pressure forming, hot pressing time of 10-90 minutes, followed by demolding and oven curing).

[0085] The diamond grinding wheel prepared in this comparative example has no toughness at all, high hardness and great brittleness. The grinding test shows that the grinding effect of ultra-thin liquid crystal glass is as follows: Figure 6 As shown, the LCD glass after grinding has serious cracks and poor finish (such as Figure 6 (shown in the middle circle).

[0086] In summary, the hardness of the binder of the present invention is HR15N < 18, which is much lower than the binders prepared by commonly used phenolic resin and polyimide resin. Conventional manual pressing can produce a depression, and it has good flexibility and low hardness; the elastic modulus is not greater than 105 N / m 2 , with good elasticity; the ultra-fine diamond grinding wheel prepared with this binder has excellent flexibility, toughness and wrapping ability for the narrow edges or narrow angles of the processed materials, can fully cover the edges of wafers and ultra-thin glass, fully grind, flexibly polish, and has a certain rebound effect. It can be used for ultra-precision grinding without brittle burns or scratches, and has small or even no chipping and a smooth surface. The surface finish Ra after processing is between 0.005-0.015μm, which fully meets the requirements of ultra-precision grinding. After changing the binder formula of this application or the preparation method of the diamond grinding wheel, it will produce burns, scratches and other phenomena when used for ultra-precision grinding, and the chipping of the chamfer is larger>50μm, the surface finish Ra>0.5μm, the grinding effect is poor, and it does not meet the requirements of ultra-precision grinding at all.

Claims

1. A binder, characterized in that The raw materials include the following percentages by mass: 25-50% thermosetting epoxy resin powder, 5-10% short fiber, 20-40% thermoplastic elastomer, 5-25% aerogel powder, and 2%-15% foaming agent; The thermosetting epoxy resin powder has a melting point range of 50-100° C. and an ICI viscosity of less than 1; The aerogel powder is a silicon dioxide aerogel powder with a nano-void structure, a thermal conductivity coefficient of less than 0.018 W / m·K at room temperature, and a porosity of more than 90%.

2. The binder according to claim 1, wherein The short fibers are selected from one or a mixture of two or more of polypropylene fibers, polyurethane fibers, carbon fibers, calcium silicate fibers, and basalt fibers; the short fibers have a diameter of 5-50 μm and a length of 50-200 μm.

3. The binder according to claim 1, wherein The thermoplastic elastomer is one or a mixture of two or more of styrene rubber, vinyl chloride rubber and polyurethane rubber; the particle size of the thermoplastic elastomer is in the range of 20-100 μm.

4. The binder according to claim 1, wherein The foaming agent is EVA foaming agent and / or NC foaming agent; the foaming temperature is 70-100°C.

5. An ultrafine diamond grinding wheel containing the binder according to any one of claims 1 to 4, characterized in that: The binder and diamond are mixed in a mass ratio of 3:7-5:5 to prepare an ultrafine diamond grinding wheel.

6. The ultrafine diamond grinding wheel according to claim 5, characterized in that The particle size of the diamond is 400#-15000#, and the diamond is polycrystalline diamond micropowder and / or single crystal diamond micropowder.

7. The method for preparing the ultrafine diamond grinding wheel according to claim 5 or 6, characterized in that: The steps include: 1) Mixing: Take the raw materials of the binder and diamond according to the proportion, mix them in a three-dimensional mixer for 0.5-2 hours, take them out and set aside; 2) Waterbath hot melt molding: Place the powder molding material mixed in step 1) into the mold cavity, cover the mold head, and make sure the bottom of the mold head is 5-10mm above the molding material layer. Place it in a water bath container under waterproof and sealed conditions. Set the water bath temperature to 70-100℃ and the water bath hot melt molding time to 80-240 minutes. After the molding time is up, remove the mold, unmold it, and proceed to the next step; 3) Hot air curing: hot air curing the diamond grinding wheel ring obtained in step 2); 4) Cold environment shrinkage toughening: Place the diamond grinding wheel ring that has been hot-air cured in step 3) in an environment of -10 to 0°C for 1 to 3 hours, take it out, and then bond it to the substrate and perform conventional processing to obtain the product.

8. The method for preparing an ultrafine diamond grinding wheel according to claim 7, wherein: The process parameters of the hot air curing in step 3) are as follows: 30°C for 15 min, 45°C for 20 min, 55°C for 20 min, 60°C for 20 min, 65°C for 15 min, 70°C for 15 min, and 80°C for 200 min.

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