Thinning grinding wheel for lithium niobate wafer and preparation method thereof

Abstract

The invention belongs to the field of semiconductor processing, and particularly relates to a thinning grinding wheel for a lithium niobate wafer and a preparation method of the thinning grinding wheel. The abrasive layer comprises the following components in parts by mass: 25-45 parts of a diamond abrasive, 20-50 parts of a resin binder, 5-10 parts of a foaming agent, 2-5 parts of zinc oxide and 2-5 parts of silicon carbide; the grinding material layer is of a porous net structure, and the porosity is 20-40%. Compared with the prior art, the grinding wheel solves the problem that in the prior art, the lithium niobate wafer is prone to fragment and edge breakage in the grinding machining process, the grinding wheel is improved, when the grinding wheel is used for grinding the lithium niobate wafer, the grinding effect is good, surface parameters are stable, the defective rate of thinning of the lithium niobate wafer is reduced, and the production efficiency is improved. And the blank of the lithium niobate wafer thinning grinding wheel in China can be filled.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor processing, and in particular relates to a thinning grinding wheel for lithium niobate wafers and a preparation method thereof. Background Art

[0002] Lithium niobate is an inorganic substance with the chemical formula LiNbO3. It is a negative crystal and ferroelectric crystal. After polarization, lithium niobate crystal has multiple properties such as piezoelectricity, ferroelectricity, photoelectricity, nonlinear optics, and thermoelectricity. It also has photorefractive effect and is a good piezoelectric transducer material, ferroelectric material, and electro-optical material. As an electro-optical material, lithium niobate plays a role in light modulation in optical communications. Its single crystal is an important material for optical waveguides, mobile phones, piezoelectric sensors, optical modulators, and various other linear and nonlinear optical applications.

[0003] Lithium niobate is a key material for making optical chips. In terms of wafer manufacturing, China, the United States and Japan have all achieved the preparation of 6-inch lithium niobate wafers, but there is still a certain gap with the 8-inch wafers and 12-inch wafers required by the global mainstream.

[0004] One of the main reasons that restrict the development of lithium niobate is that lithium niobate wafers are very fragile and are prone to breakage and edge collapse during the grinding process, which results in their yield and good rate being insufficient for industrial production and commercial use. Therefore, it is necessary to provide a grinding process that can reduce the defective rate during the processing of lithium niobate wafers. Summary of the invention

[0005] The purpose of the present invention is to provide a thinning grinding wheel for lithium niobate wafers and a preparation method thereof in order to solve at least one of the above problems, so as to solve the problem that lithium niobate wafers are very likely to break and collapse during the grinding process in the prior art. This solution improves the grinding wheel itself, and when it is used for lithium niobate wafers, the grinding effect is good, the surface parameters are stable, and the defective rate of lithium niobate wafer thinning is reduced, which can fill the gap in domestic lithium niobate wafer thinning grinding wheels.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The first aspect of the present invention discloses a thinning grinding wheel for lithium niobate wafers, which is obtained by combining a base body and an abrasive layer;

[0008] The abrasive layer comprises the following components in parts by weight: 25-45 parts of diamond abrasive, 20-50 parts of resin binder, 5-10 parts of foaming agent, 2-5 parts of zinc oxide and 2-5 parts of silicon carbide;

[0009] The abrasive layer is a porous mesh structure with a porosity of 20-40%.

[0010] Preferably, the particle size of the diamond abrasive is 2000#-4000#.

[0011] Preferably, the resin binder is prepared by the following steps:

[0012] The polyimide resin, molybdenum disulfide, cryolite and potassium sulfate are uniformly mixed and dried, and then ball-milled and sieved to obtain a resin binder;

[0013] Among them, by mass: 40-60 parts of polyimide resin, 30-40 parts of molybdenum disulfide, 10-20 parts of cryolite, and 10-20 parts of potassium sulfate.

[0014] Preferably, the drying temperature is 100-120° C., and the time is 2-4 hours; the ball milling time is 1-2 hours; and the screening is through a 600-mesh sieve.

[0015] Preferably, the foaming agent is an alkane foaming agent, which is a mixture of cyclopentane and isopentane in a volume ratio of 2:8.

[0016] Preferably, the substrate is an annular structure made of aluminum alloy, on which a groove for fixing the abrasive layer is provided, and on the inner side thereof drainage holes for flushing the abrasive chips by water flow are provided along the annular direction.

[0017] More preferably, the drainage holes are evenly distributed, and 36 drainage holes are provided.

[0018] The second aspect of the present invention discloses a method for preparing a thinning grinding wheel for lithium niobate wafers as described above, comprising the following steps:

[0019] S1: diamond abrasive is added to acetone solvent for ultrasonic treatment and then dried;

[0020] S2: Mix zinc oxide, silicon carbide and the diamond abrasive pretreated in step S1 and sieve the mixture;

[0021] S3: mixing the resin binder, the foaming agent and the prefabricated material obtained in step S2 and sieving the mixture;

[0022] S4: hot pressing the molding material obtained in step S3, keeping it warm and then cooling it;

[0023] S5: vacuum sintering the grinding wheel block obtained in step S4 to obtain an abrasive layer;

[0024] S6: Mechanically process the abrasive layer and the substrate obtained in step S5 to obtain the thinning grinding wheel for lithium niobate wafers.

[0025] Preferably, in step S1, the ultrasonic treatment is performed at 20000 Hz for 1-2 hours; and the drying is performed at 100-120° C. for 1-2 hours.

[0026] Preferably, in step S2 and step S3, the screening is through a 600-mesh sieve.

[0027] Preferably, in step S4, the pressing temperature of the hot pressing molding is 140-180°C, the pressing time is 2-4h, the pressure is 2.5-5MPa, and the air is released 10-20 times during the pressing process; and the heat preservation is at 120-140°C for 2-4h.

[0028] Preferably, in step S5, the vacuum sintering is to increase the temperature to 700-900°C in a vacuum furnace according to a temperature curve, and the temperature curve is: gradually increase the temperature from room temperature to 600-800°C, sinter for 3 hours; continue to stepwise increase the temperature to 700-900°C, sinter for 1 hour; keep warm for 4 hours; the total time of the vacuum sintering is 12-24 hours. The stepwise temperature increase is a process in which the temperature increases monotonically.

[0029] Preferably, in step S6, the mechanical processing is drying after bonding, and specifically, the prepared abrasive layer can be fixed on the substrate by using composite glue and dried for 2-4 hours to complete the mechanical processing.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The lithium niobate wafer thinning grinding wheel provided by the present invention is a porous mesh structure grinding wheel, which uses an alkane foaming agent and has a porosity of 20-40%. The lithium niobate wafer thinning sand prepared by the method has good grinding surface parameters and no broken pieces. At the same time, the grinding wheel also has the characteristics of long dressing cycle, stable continuous processing surface parameters, etc.

[0032] The porosity of the abrasive layer of the grinding wheel is increased according to the foaming agent used. The increased porosity can increase the self-sharpening property of the grinding wheel, and ensure that the abrasive layer falls off regularly during grinding. In this way, the grinding chips generated by grinding will not block the surface of the abrasive layer, ensuring that the grinding wheel is sharp and has a good grinding effect.

[0033] The added silicon carbide and zinc oxide make the abrasive layer reach an appropriate hardness, ensuring that the workpiece will not be scratched during grinding and improving the surface parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The surface morphology data of the lithium niobate wafer after being ground by the thinning grinding wheel of the present invention is detected by the ADE9600 flatness detector;

[0035] Figure 2This is a TEM image of a lithium niobate wafer after being ground with the thinning grinding wheel of the present invention and after being sliced ​​by FIB. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the following description, unless otherwise specified, the reagents used are conventional commercially available products, and the methods used are well known in the art.

[0038] The invention proposes a lithium niobate wafer thinning grinding wheel and a preparation method thereof. The lithium niobate wafer thinning grinding wheel prepared by the method has good grinding effect and stable surface parameters, reduces the defective rate of lithium niobate wafer thinning, and fills the gap of lithium niobate wafer thinning grinding wheels in China.

[0039] A lithium niobate wafer thinning grinding wheel comprises a base body and an abrasive layer.

[0040] The base is an aluminum alloy ring structure with a groove for fixing the abrasive layer and 36 drainage holes on the inner side of the ring. The drainage holes are evenly distributed to ensure that a stable water flow can wash away the grinding chips during the grinding process.

[0041] The raw materials of the abrasive layer include, by mass fraction, 25-45 parts of diamond abrasive, 20-50 parts of bonding agent, 5-10 parts of foaming agent, 2-5 parts of zinc oxide, and 2-5 parts of silicon carbide powder.

[0042] The following introduces various materials used in the lithium niobate wafer thinning grinding wheel, wherein each component is added to improve the overall performance of the grinding wheel.

[0043] Diamond abrasive is a commonly used abrasive for grinding tools. It is very hard, has good grinding effect, smooth grinding surface, and is very durable. It consumes less in continuous grinding and reduces the wear ratio. According to different grinding conditions, one or more different diamond abrasives (such as different particle sizes) can be selected for grinding.

[0044] The resin binder includes polyimide resin, molybdenum disulfide, cryolite and potassium sulfate. The advantages of the resin binder are that the binder has high elasticity, is suitable for high-speed cutting, has good toughness, and can maintain the surface temperature of the grinding wheel during the grinding process, so that the surface of the ground lithium niobate wafer will not be burned.

[0045] The foaming agent used in the present invention is an alkane foaming agent, which is a physical foaming agent and has a composition of cyclopentane / isopentane mixture. It is completely gasified at about 50° C. and has a good foaming effect, so that the grinding wheel abrasive layer has a continuous porous structure.

[0046] Zinc oxide has a significant hardening effect in the production of grinding wheels, which can enhance the hardness and strength of the grinding wheel. This is because the zinc oxide particles can fill the pores and cracks of the grinding wheel, enhance the compactness and density of the grinding wheel, and thus improve the hardness and strength of the grinding wheel.

[0047] The hardness of silicon carbide is second only to diamond. It has extremely high hardness and excellent wear resistance. It also has good thermal conductivity. It can enhance the hardness, wear resistance and thermal conductivity of the grinding wheel, thereby extending the service life of the grinding wheel.

[0048] The preparation method of the lithium niobate wafer thinning grinding wheel comprises the following steps:

[0049] (1) The diamond abrasive was placed in an acetone solvent and subjected to ultrasonic treatment at 20,000 Hz for 1-2 hours, and then dried in an oven at 100-120° C. for 1-2 hours.

[0050] (2) The diamond abrasive treated in (1) is mixed with zinc oxide and silicon carbide powder, and then passed through a 600-mesh sieve to obtain a preform.

[0051] (3) The binder, foaming agent and the preformed material prepared in (2) are mixed and passed through a 600-mesh sieve to obtain a shaped abrasive.

[0052] (4) placing the shaped abrasive prepared in step (3) into a mold, and then placing it into a hot press for hot pressing. After the hot pressing is completed, taking out the mold, placing it in an oven at 120-140° C. for 2-4 hours, and removing the mold after cooling to obtain a grinding wheel block to be sintered.

[0053] (5) Place the grinding wheel block in step (4) into a vacuum furnace and gradually raise the temperature to 700-900° C. and sinter for 12-24 hours according to the temperature curve.

[0054] During the sintering process, the temperature curve is divided into the following three stages: in the first stage, the temperature is gradually increased from room temperature to 600-800°C and sintered for 3 hours; in the second stage, the temperature is gradually increased from 600-800°C to 700-900°C and sintered for 1 hour; in the third stage, 700-900°C is kept for 4 hours and naturally cooled to room temperature.

[0055] (6) The grinding wheel block sintered in step (5) is taken out, cooled to room temperature, and mechanically processed with the substrate to obtain a lithium niobate wafer thinning grinding wheel.

[0056] The diamond abrasive particle size is 2000#-4000#.

[0057] The resin binder comprises polyimide resin, molybdenum disulfide, cryolite and potassium sulfate (by mass: 40-60 parts of polyimide resin, 30-40 parts of molybdenum disulfide, 10-20 parts of cryolite, 10-20 parts of potassium sulfate), and the binder is processed as follows: after all the raw materials are fully mixed, they are dried in an oven at 100-120°C for 2-4 hours, then put into a pot-type ball mill for 1-2 hours, and passed through a 600-mesh screen to obtain the resin binder. The grinding wheel made of the resin binder prepared in this way has good toughness, stable grinding surface, and long dressing cycle.

[0058] The foaming agent is an expandable microsphere foaming agent, the shell is a thermoplastic acrylic polymer, the content is an alkane foaming agent, and the composition is cyclopentane and isopentane mixed in a volume ratio of 2:8. The foaming agent is completely decomposed into gas at high temperature, has a significant foaming effect, and will not pollute the components of the abrasive layer.

[0059] In the step (4), the pressing temperature is 140-180° C., the pressing time is 2-4 h, the pressure is 2.5-5 MPa, and air is released 10-20 times during the pressing process.

[0060] In the step (6), the mechanical processing is carried out in the form of drying after bonding.

[0061] Example 1

[0062] A lithium niobate wafer thinning grinding wheel and a preparation method thereof, wherein the components thereof include, by mass fraction, 35 parts of diamond abrasive, 45 parts of a binder, 10 parts of a foaming agent, 5 parts of zinc oxide, and 5 parts of silicon carbide powder.

[0063] The preparation method of the lithium niobate wafer thinning grinding wheel comprises the following steps:

[0064] (1) The diamond abrasive was placed in an acetone solvent and subjected to ultrasonic treatment at 20,000 Hz for 1 h, and then dried in an oven at 100°C for 1 h.

[0065] (2) The diamond abrasive and silicon carbide powder treated in (1) are mixed and then passed through a 600-mesh sieve to obtain a preform.

[0066] (3) The binder, foaming agent and the preformed material prepared in (2) are mixed and passed through a 600-mesh sieve to obtain a shaped abrasive.

[0067] (4) placing the shaped abrasive prepared in step (3) into a mold, and then placing it into a hot press for hot pressing. After the hot pressing is completed, taking out the mold, placing it in an oven at 120° C. for 2 h, and removing the mold after cooling to obtain a grinding wheel block to be sintered.

[0068] (5) Place the grinding wheel block in step (4) into a vacuum furnace and gradually increase the temperature to 700° C. and sinter for 12 h.

[0069] (6) The grinding wheel block sintered in step (5) is taken out, cooled to room temperature, and mechanically processed with the substrate to obtain a lithium niobate wafer thinning grinding wheel.

[0070] The diamond abrasive particle size is 2000#.

[0071] The resin binder comprises polyimide resin, molybdenum disulfide, cryolite and potassium sulfate (polyimide resin, molybdenum disulfide, cryolite and potassium sulfate are calculated by mass: 40 parts of polyimide resin, 30 parts of molybdenum disulfide, 10 parts of cryolite and 20 parts of potassium sulfate). The binder is processed as follows: after all the raw materials are fully mixed, they are dried in an oven at 100°C for 2 hours, then put into a pot ball mill for 1 hour, and passed through a 600-mesh sieve to obtain the resin binder. The grinding wheel made of the resin binder prepared in this way has good toughness, stable grinding surface and long dressing cycle.

[0072] The foaming agent is an expandable microsphere foaming agent, the shell is a thermoplastic acrylic polymer, the content is an alkane foaming agent, and the composition is a mixture of cyclopentane and isopentane in a ratio of 2:8. The foaming agent is completely decomposed into gas at high temperature, has a significant foaming effect, and will not pollute the components of the abrasive layer.

[0073] In the step (4), the pressing temperature is 140° C., the pressing time is 2 h, the pressure is 2.5 MPa, and air is released 20 times during the pressing process.

[0074] The grinding wheel in Example 1 was used for lithium niobate wafer thinning test. Experimental items: Grinding lithium niobate wafers on a DISCO 8761 thinning machine, with a single-side grinding amount of 100 μm, a fine grinding amount of 20 μm, a grinding wheel speed of 4800 rpm, grinding 100 wafers without trimming, no broken wafers, and surface parameters TTV, WARP, BOW, etc. were all within the qualified range (TTV within 5 μm, WARP within 30 μm, BOW between -15 and 15 μm, the same below).

[0075] Example 2

[0076] A lithium niobate wafer thinning grinding wheel and a preparation method thereof, wherein the components thereof include, by mass fraction, 40 parts of diamond abrasive, 50 parts of a binder, 5 parts of a foaming agent, 3 parts of zinc oxide, and 2 parts of silicon carbide powder.

[0077] The preparation method of the lithium niobate wafer thinning grinding wheel comprises the following steps:

[0078] (1) The diamond abrasive was placed in an acetone solvent and subjected to ultrasonic treatment at 20,000 Hz for 1 h, and then dried in an oven at 110°C for 1 h.

[0079] (2) The diamond abrasive and silicon carbide powder treated in (1) are mixed and then passed through a 600-mesh sieve to obtain a preform.

[0080] (3) The binder, foaming agent and the preformed material prepared in (2) are mixed and passed through a 600-mesh sieve to obtain a shaped abrasive.

[0081] (4) placing the shaped abrasive prepared in step (3) into a mold, and then placing it into a hot press for hot pressing. After the hot pressing is completed, taking out the mold, placing it in an oven at 130° C. for 2 h, and removing the mold after cooling to obtain a grinding wheel block to be sintered.

[0082] (5) Place the grinding wheel block in step (4) into a vacuum furnace and gradually raise the temperature to 800° C. and sinter for 12 h.

[0083] (6) The grinding wheel block sintered in step (5) is taken out, cooled to room temperature, and mechanically processed with the substrate to obtain a lithium niobate wafer thinning grinding wheel.

[0084] The diamond abrasive particle size is 3000#.

[0085] The resin binder comprises polyimide resin, molybdenum disulfide, cryolite and potassium sulfate (polyimide resin, molybdenum disulfide, cryolite and potassium sulfate are calculated by mass: 50 parts of polyimide resin, 30 parts of molybdenum disulfide, 10 parts of cryolite and 10 parts of potassium sulfate). The binder is processed as follows: after all the raw materials are fully mixed, they are dried in an oven at 110°C for 2 hours, then put into a pot ball mill for 1 hour, and passed through a 600-mesh sieve to obtain the resin binder. The grinding wheel made of the resin binder prepared in this way has good toughness, stable grinding surface and long dressing cycle.

[0086] The foaming agent is an expandable microsphere foaming agent, the shell is a thermoplastic acrylic polymer, the content is an alkane foaming agent, and the composition is a mixture of cyclopentane and isopentane in a ratio of 2:8. The foaming agent is completely decomposed into gas at high temperature, has a significant foaming effect, and will not pollute the components of the abrasive layer.

[0087] In the step (4), the pressing temperature is 160° C., the pressing time is 2 h, the pressure is 2.5 MPa, and air is released 20 times during the pressing process.

[0088] The grinding wheel in Example 2 was used for lithium niobate wafer thinning test. Experimental items: Lithium niobate wafers were ground on a DISCO 8761 thinning machine, with a single-side grinding amount of 100 μm, a fine grinding amount of 20 μm, a grinding wheel speed of 4800 rpm, 100 wafers were ground without trimming, no broken wafers, and surface parameters such as TTV, WARP, and BOW were all within the qualified range.

[0089] Example 3

[0090] A lithium niobate wafer thinning grinding wheel and a preparation method thereof, wherein the components thereof include, by mass fraction, 35 parts of diamond abrasive, 50 parts of a binder, 10 parts of a foaming agent, 3 parts of zinc oxide, and 2 parts of silicon carbide powder.

[0091] The preparation method of the lithium niobate wafer thinning grinding wheel comprises the following steps:

[0092] (1) The diamond abrasive was placed in an acetone solvent and subjected to ultrasonic treatment at 20,000 Hz for 1 h, and then dried in an oven at 120°C for 1 h.

[0093] (2) The diamond abrasive and silicon carbide powder treated in (1) are mixed and then passed through a 600-mesh sieve to obtain a preform.

[0094] (3) The binder, foaming agent and the preformed material prepared in (2) are mixed and passed through a 600-mesh sieve to obtain a shaped abrasive.

[0095] (4) placing the shaped abrasive prepared in step (3) into a mold, and then placing it into a hot press for hot pressing. After the hot pressing is completed, taking out the mold, placing it in an oven at 140° C. for 2 h, and removing the mold after cooling to obtain a grinding wheel block to be sintered.

[0096] (5) Place the grinding wheel block in step (4) into a vacuum furnace and gradually raise the temperature to 900° C. and sinter for 12 h.

[0097] (6) The grinding wheel block sintered in step (5) is taken out, cooled to room temperature, and mechanically processed with the substrate to obtain a lithium niobate wafer thinning grinding wheel.

[0098] The diamond abrasive particle size is 4000#.

[0099] The resin binder comprises polyimide resin, molybdenum disulfide, cryolite and potassium sulfate (polyimide resin, molybdenum disulfide, cryolite and potassium sulfate are calculated by mass: 40 parts of polyimide resin, 30 parts of molybdenum disulfide, 20 parts of cryolite and 10 parts of potassium sulfate), and the binder is processed as follows: after all the raw materials are fully mixed, they are dried in an oven at 120°C for 2 hours, then put into a pot ball mill for 1 hour, and passed through a 600-mesh screen to obtain the resin binder. The grinding wheel made of the resin binder prepared in this way has good toughness, stable grinding surface and long dressing cycle.

[0100] The foaming agent is an expandable microsphere foaming agent, the shell is a thermoplastic acrylic polymer, the content is an alkane foaming agent, and the composition is a mixture of cyclopentane and isopentane in a ratio of 2:8. The foaming agent is completely decomposed into gas at high temperature, has a significant foaming effect, and will not pollute the components of the abrasive layer.

[0101] In the step (4), the pressing temperature is 180° C., the pressing time is 2 h, the pressure is 2.5 MPa, and air is released 20 times during the pressing process.

[0102] The grinding wheel in Example 3 was used for lithium niobate wafer thinning test. Experimental items: Lithium niobate wafers were ground on a DISCO 8761 thinning machine, with a single-side grinding amount of 100 μm, a fine grinding amount of 20 μm, a grinding wheel speed of 4800 rpm, 100 wafers were ground without trimming, no broken wafers, and surface parameters such as TTV, WARP, and BOW were all within the qualified range.

[0103] Figure 1 and Figure 2 The grinding effects of lithium niobate wafers after grinding by the present invention are shown respectively. It can be seen that Figure 1 The surface morphology is good, including TTV and STIR. Figure 2 The damaged layer after grinding is controlled within 200nm, while other grinding methods are usually 200-300nm.

[0104] Comparative Example

[0105] A ceramic bonded cubic boron nitride grinding wheel (GF01 series from Japan DISCO) was used for a grinding comparison test. Experimental items: Grinding lithium niobate wafers on a grinding machine, with a single-side grinding amount of 100μm, a grinding speed of 4800rpm, and grinding 100 wafers. There was a phenomenon of chip breakage, and the TTV was 2-5μm.

[0106] Comparing the grinding effects of the thinned grinding wheel of the present solution with those of the existing ceramic bonded cubic boron nitride grinding wheel, it is shown that the present invention not only ensures the surface physical characteristics of the lithium niobate wafer after grinding, but also reduces broken pieces and improves the yield.

[0107] In addition, the correction cycle of a general grinding wheel is only 2000-3000 pieces, while the correction cycle of the thinning grinding wheel provided by the present invention can reach 4000-5000 pieces, and the continuous processing surface parameters are stable, such as surface roughness, TTV, etc. are all within the qualified range, indicating that the thinning grinding wheel has the characteristics of long correction cycle and stable continuous processing surface parameters, which can effectively reduce the scrap rate, shorten the cycle of line shutdown maintenance and replacement, reduce production costs, and improve production rhythm.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0109] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A thinning grinding wheel for lithium niobate wafers, characterized in that: It is obtained by combining a base and an abrasive layer; The abrasive layer comprises the following components in parts by weight: 25-45 parts of diamond abrasive, 20-50 parts of resin binder, 5-10 parts of foaming agent, 2-5 parts of zinc oxide and 2-5 parts of silicon carbide; The abrasive layer is a porous mesh structure with a porosity of 20-40%.

2. A thinning grinding wheel for lithium niobate wafers according to claim 1, characterized in that: The particle size of the diamond abrasive is 2000#-4000#.

3. A thinning grinding wheel for lithium niobate wafer according to claim 1, characterized in that: The resin binder is prepared by the following steps: The polyimide resin, molybdenum disulfide, cryolite and potassium sulfate are uniformly mixed and dried, and then ball-milled and sieved to obtain a resin binder.

4. A thinning grinding wheel for lithium niobate wafers according to claim 3, characterized in that: The drying temperature is 100-120° C., and the time is 2-4 hours; the ball milling time is 1-2 hours; and the screening is through a 600-mesh sieve.

5. The thinning grinding wheel for lithium niobate wafer according to claim 1, characterized in that: The foaming agent is an alkane foaming agent, which is a mixture of cyclopentane and isopentane in a volume ratio of 2:

8.

6. A method for preparing a thinning grinding wheel for lithium niobate wafers according to any one of claims 1 to 5, characterized in that: The steps include: S1: diamond abrasive is added to acetone solvent for ultrasonic treatment and then dried; S2: Mix zinc oxide, silicon carbide and the diamond abrasive pretreated in step S1 and sieve the mixture; S3: mixing the resin binder, the foaming agent and the prefabricated material obtained in step S2 and sieving the mixture; S4: hot pressing the molding material obtained in step S3, keeping it warm and then cooling it; S5: vacuum sintering the grinding wheel block obtained in step S4 to obtain an abrasive layer; S6: Mechanically process the abrasive layer and the substrate obtained in step S5 to obtain the thinning grinding wheel for lithium niobate wafers.

7. The method for preparing a thinning grinding wheel for lithium niobate wafer according to claim 6, characterized in that: In step S1, the ultrasonic treatment is performed at 20000 Hz for 1-2 hours; and the drying is performed at 100-120° C. for 1-2 hours.

8. The method for preparing a thinning grinding wheel for lithium niobate wafer according to claim 6, characterized in that: In step S2 and step S3, the screening is through a 600-mesh sieve.

9. The method for preparing a thinning grinding wheel for lithium niobate wafer according to claim 6, characterized in that: In step S4, the pressing temperature of the hot pressing molding is 140-180°C, the pressing time is 2-4h, the pressure is 2.5-5MPa, and the air is released 10-20 times during the pressing process; and the heat preservation is kept at 120-140°C for 2-4h.

10. The method for preparing a thinning grinding wheel for lithium niobate wafer according to claim 6, characterized in that: In step S5, the vacuum sintering is to heat the temperature to 700-900°C in a vacuum furnace according to a temperature curve, and the temperature curve is: gradually heating from room temperature to 600-800°C, sintering for 3 hours; continuing to stepwise heat up to 700-900°C, sintering for 1 hour; keeping warm for 4 hours; the total time of the vacuum sintering is 12-24 hours.

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