Rough grinding liquid for diamond substrate, preparation method of rough grinding liquid and rough grinding method of diamond substrate

Abstract

The invention discloses coarse grinding liquid for a diamond substrate, a preparation method of the coarse grinding liquid and a coarse grinding method of the diamond substrate, and relates to the technical field of diamond processing. The coarse grinding liquid for the diamond substrate comprises the following components in parts by mass: 0.5-1.5 parts of diamond, 0.1-1 part of a dispersing agent, 1-5 parts of a pH regulator, 0.1-1 part of a suspending agent and 88-98 parts of water, wherein the D50 of the diamond is 10 [mu] m-50 [mu] m; the suspending agent comprises at least one of xanthan gum, carbomer, sodium polyacrylate and bentonite; the dispersing agent comprises at least one of polymaleic anhydride, sodium pyrophosphate, anhydrous sodium metasilicate and polyacrylamide. According to the technical scheme, by adjusting the particle size of the grinding material and adjusting the composition of the suspending agent and the dispersing agent, the problems of low grinding rate, large surface roughness and high total thickness deviation of the existing grinding liquid for the diamond substrate can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of diamond processing, and in particular to a rough grinding liquid for a diamond substrate and a preparation method thereof, and a rough grinding method for a diamond substrate. Background Art

[0002] Diamond, as a material with extremely high hardness and brittle properties, is widely used in various fields, such as electronics, optics, tool processing, etc. At present, diamond crystals need to be cut, ground, polished and other processes before they can be used industrially. The tiny unevenness and impurities on the surface of diamond will affect its optical and electronic properties. Due to the extremely high hardness of diamond, traditional polishing methods often cannot achieve atomic-level roughness control of the diamond surface, which greatly limits the application of diamond.

[0003] The commonly used diamond polishing scheme is generally divided into three processes: rough grinding, fine grinding and fine polishing. The purpose of rough grinding is to remove large defects, cracks and uneven parts on the surface; fine grinding (generally mechanical polishing) is to quickly remove the surface damage layer caused by the previous grinding process while ensuring flatness, and reduce the surface roughness; fine polishing (generally chemical mechanical polishing) is to further improve the micro-roughness of the crystal surface through chemical corrosion and mechanical action to achieve a high surface finish. At present, the rough grinding liquid used for diamond substrates mostly uses single crystal diamond for rough grinding. In the actual production process, there are problems such as low grinding rate, large surface roughness, and high TTV (Total Thickness Variation, TTV).

[0004] Therefore, there is an urgent need to develop an efficient and low-cost rough grinding fluid to solve the problems of low grinding rate, large surface roughness and high TTV in the existing rough grinding fluid for diamond substrates. Summary of the invention

[0005] The main purpose of the present invention is to provide a rough grinding liquid for diamond substrates and a preparation method thereof, and a rough grinding method for diamond substrates, aiming to solve the problems of low grinding rate, large surface roughness and high TTV existing in the existing rough grinding liquid for diamond substrates.

[0006] To achieve the above object, the present invention provides a rough grinding liquid for diamond substrate, comprising the following components by weight: 0.5-1.5 parts of diamond, 0.1-1 parts of dispersant, 1-5 parts of pH regulator, 0.1-1 parts of suspending agent, and 88-98 parts of water; wherein:

[0007] The D50 of the diamond is 10 μm to 50 μm;

[0008] The suspending agent comprises at least one of xanthan gum, carbomer, sodium polyacrylate and bentonite;

[0009] The dispersant includes at least one of polymaleic anhydride, sodium pyrophosphate, anhydrous sodium metasilicate and polyacrylamide.

[0010] In one embodiment, the pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine and ammonia water.

[0011] In one embodiment, the pH value of the rough grinding liquid for diamond substrate is 7-9.

[0012] In one embodiment, the viscosity of the rough grinding liquid for diamond substrate is 1500-3000 mPa·s.

[0013] The present invention provides a method for preparing a rough grinding liquid for a diamond substrate, comprising the following steps:

[0014] A1. Mix diamond and water to obtain a diamond solution;

[0015] A2, mixing the diamond solution, the dispersant and the suspending agent to obtain a mixed solution;

[0016] A3. Adding a pH regulator to the mixed solution to obtain the rough grinding solution for diamond substrate.

[0017] In one embodiment, the step A1 comprises:

[0018] Diamond and water are mixed in a stirred tank to obtain a diamond solution; wherein:

[0019] The frequency of the stirring kettle is 15 to 20 Hz; and / or,

[0020] The stirring time of the stirring tank is 20 to 40 minutes.

[0021] In one embodiment, the step A1 comprises:

[0022] First, add water into the stirring kettle, start the stirring kettle, then add diamond, mix, and obtain a diamond solution.

[0023] In one embodiment, step A2 comprises:

[0024] The diamond solution, the dispersant and the suspending agent are mixed in a stirring tank to obtain a mixed solution; wherein:

[0025] The frequency of the stirring kettle is 25 to 35 Hz; and / or,

[0026] The stirring time of the stirring tank is 20 to 40 minutes.

[0027] The present invention provides a rough grinding method for a diamond substrate, comprising the following steps:

[0028] B1. Providing a diamond substrate;

[0029] B2, applying a rough grinding liquid on the diamond substrate, and performing rough grinding to obtain a rough ground diamond substrate;

[0030] Wherein, the rough grinding liquid is the rough grinding liquid for diamond substrate described in the above technical solution or the rough grinding liquid prepared by the preparation method of the rough grinding liquid for diamond substrate described in the above technical solution.

[0031] In one embodiment, in the step B2, the rough grinding rate is 10-12 μm / h.

[0032] The beneficial effects of the technical solution of the present invention are as follows:

[0033] The rough grinding liquid provided by the technical solution of the present invention uses micron diamond with a particle size of 10μm to 50μm as an abrasive, which reduces the possibility of scratches during the rough grinding process; and the micron diamond has excellent hardness and wear resistance, and the characteristics of uniform particle size distribution, which helps to achieve consistent processing effects during the rough grinding process, reduce surface roughness and TTV, and improve processing accuracy; the micron diamond also has high purity and low impurity content, which can reduce the possibility of introducing additional pollutants during the rough grinding process, and help improve the quality of the processed surface; specific suspending agents and dispersants are selected to make the abrasive evenly distributed in the liquid phase, which is beneficial to improving the quality of the processed surface. Therefore, the technical solution of the present invention adjusts the abrasive particle size and the composition of the suspending agent and the dispersant to obtain a coarse grinding liquid with good dispersibility and good suspension, which can keep the abrasive in the grinding liquid in a uniform and non-precipitated state for a long time. The coarse grinding liquid provided by the technical solution of the present invention can be used for grinding, which can effectively avoid scratches on the workpiece surface, improve the grinding rate during the coarse grinding process, and make the processed diamond substrate have a superior processing surface with a small total thickness deviation. It can be used to improve the problems of low grinding rate, large surface roughness, and high total thickness deviation in the existing coarse grinding liquid for diamond substrates. In addition, the coarse grinding liquid provided by the technical solution of the present invention does not require complex modification of the abrasive, does not require the addition of special additives, and does not require a special grinding process. It has the advantages of low cost and high efficiency, which is conducive to large-scale application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of 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.

[0035] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0036] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] Diamond, as a material with extremely high hardness and brittle properties, is widely used in various fields, such as electronics, optics, tool processing, etc. At present, diamond crystals need to be cut, ground, polished and other processes before they can be used industrially. The tiny unevenness and impurities on the surface of diamond will affect its optical and electronic properties. Due to the extremely high hardness of diamond, traditional polishing methods often cannot achieve atomic-level roughness control of the diamond surface, which greatly limits the application of diamond.

[0038] Commonly used diamond polishing schemes are generally divided into three processes: rough grinding, fine grinding and fine polishing. The purpose of rough grinding is to remove large defects, cracks and uneven parts on the surface; fine grinding (generally mechanical polishing) is to quickly remove the surface damage layer caused by the previous grinding process while ensuring flatness, thereby reducing the surface roughness; fine polishing (generally chemical mechanical polishing) is to further improve the micro-roughness of the crystal surface through chemical corrosion and mechanical action to achieve a high surface finish.

[0039] At present, most of the rough grinding fluids used for diamond substrates use large-particle single-crystal diamonds with a particle size of 50 to 100 μm for rough grinding. The grinding speed is slow, and after rough grinding, the surface roughness of the diamond substrate is usually 300 to 500 nm, and the TTV result is usually 20 to 30 μm. Therefore, it is urgent to develop an efficient and low-cost rough grinding fluid to solve the problems of low grinding rate, large surface roughness, and high total thickness deviation in the existing rough grinding fluids used for diamond substrates.

[0040] In view of this, the present invention provides a rough grinding liquid for a diamond substrate, the rough grinding liquid for a diamond substrate comprising the following components in parts by mass: 0.5-1.5 parts of diamond, 0.1-1 parts of a dispersant, 1-5 parts of a pH regulator, 0.1-1 parts of a suspending agent, and 88-98 parts of water; wherein:

[0041] The D50 of the diamond is 10 μm to 50 μm;

[0042] The suspending agent comprises at least one of xanthan gum, carbomer, sodium polyacrylate and bentonite;

[0043] The dispersant includes at least one of polymaleic anhydride, sodium pyrophosphate, anhydrous sodium metasilicate and polyacrylamide.

[0044] The rough grinding liquid provided by the technical solution of the present invention uses micron diamond with a particle size of 10μm to 50μm as an abrasive, which reduces the possibility of scratches during the rough grinding process; and the micron diamond has excellent hardness and wear resistance, and the characteristics of uniform particle size distribution, which helps to achieve consistent processing effects during the rough grinding process, reduce surface roughness and TTV, and improve processing accuracy; the micron diamond also has high purity and low impurity content, which can reduce the possibility of introducing additional pollutants during the rough grinding process, and help improve the quality of the processed surface; specific suspending agents and dispersants are selected to make the abrasive evenly distributed in the liquid phase, which is beneficial to improving the quality of the processed surface. Therefore, the technical solution of the present invention adjusts the abrasive particle size and the composition of the suspending agent and the dispersant to obtain a coarse grinding liquid with good dispersibility and good suspension, which can keep the abrasive in the grinding liquid in a uniform and non-precipitated state for a long time. The coarse grinding liquid provided by the technical solution of the present invention can be used for grinding, which can effectively avoid scratches on the workpiece surface, improve the grinding rate during the coarse grinding process, and make the processed diamond substrate have a superior processing surface with a small total thickness deviation. Therefore, it can be used to improve the problems of low grinding rate, large surface roughness, and high total thickness deviation existing in the existing grinding liquid for diamond substrates. In addition, the coarse grinding liquid provided by the technical solution of the present invention does not require complex modification of the abrasive, does not require the addition of special additives, and does not require a special grinding process. It has the advantages of low cost and high efficiency, which is conducive to large-scale application.

[0045] It should be noted that the dispersant is used to evenly disperse the abrasive in the liquid medium. If the dispersant is not used, the abrasive particles in the grinding liquid are prone to agglomeration, resulting in poor grinding effect and high surface roughness; the suspending agent is used to improve the suspension stability of the abrasive in the grinding liquid, prevent precipitation, and also has a certain lubricating effect, which is beneficial to improving the quality of the processed surface. The conventional suspending agent used for diamond substrates is cellulose, which has a high viscosity and will affect the processing; the conventional dispersant used for diamond substrates is an organic dispersant. Compared with conventional suspending agents, the suspending agent of the technical solution of the present invention can maintain a better suspension effect under conditions of lower viscosity, has little impact on processing, and is beneficial to improving the quality of the processed surface; compared with conventional dispersants, the dispersant of the technical solution of the present invention is an inorganic dispersant, which has a more stable composition and a better dispersion effect on diamond.

[0046] In an embodiment of the present invention, the pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine and ammonia water.

[0047] In an embodiment of the present invention, the pH value of the rough grinding liquid for diamond substrate is 7 to 9. Setting the pH value of the rough grinding liquid within the above range is conducive to the suspending agent maintaining a good suspension effect.

[0048] In an embodiment of the present invention, the viscosity of the rough grinding liquid for diamond substrate is 1500-3000 mPa·s. If the viscosity is too low, the grinding liquid is easy to be thrown out from the grinding disc during the grinding process, affecting the grinding rate; if the viscosity is too high, the fluidity of the grinding liquid is relatively poor, the chip removal ability is low, and the grinding chips are easy to clog the grinding disc, causing problems such as high disc temperature and large TTV. Setting the viscosity of the rough grinding liquid to 1500-3000 mPa·s is conducive to controlling the surface shape and grinding rate of the workpiece being processed.

[0049] The present invention provides a method for preparing a rough grinding liquid for a diamond substrate, comprising the following steps:

[0050] A1. Mix diamond and water to obtain a diamond solution;

[0051] A2, mixing the diamond solution, the dispersant and the suspending agent to obtain a mixed solution;

[0052] A3. Adding a pH regulator to the mixed solution to obtain the rough grinding solution for diamond substrate.

[0053] The preparation method of the present invention limits the order of adding the components. Specifically, first, diamond is slowly added to water to avoid diamond agglomeration in water due to too fast addition; then, a dispersant and a suspending agent are added to make the mixed solution in a stable suspension state; finally, a pH regulator is added to make the suspending agent effective, and the rough grinding liquid for diamond substrate can be obtained. The rough grinding liquid prepared by the preparation method provided by the technical solution of the present invention has good stability and polishing effect.

[0054] In the embodiment of the present invention, the diamond is screened for large particles before step A1, so that the particle size of the diamond is within the range of 10 μm to 50 μm. During the grinding process, large particles are prone to produce deep scratches on the surface of the diamond substrate due to their large size and high penetration depth, causing scratches. Therefore, before rough grinding, the abrasive is screened for large particles to reduce scratches and improve the grinding effect and product quality.

[0055] In an embodiment of the present invention, step A1 includes:

[0056] Diamond and water are mixed in a stirred tank to obtain a diamond solution; wherein:

[0057] The frequency of the stirring kettle is 15 to 20 Hz;

[0058] The stirring time of the stirring tank is 20 to 40 minutes.

[0059] The technical solution of the present invention selects to add abrasive at a lower frequency, and sets the frequency and stirring time of the stirring kettle within the above range, so that the diamond powder is dispersed more fully.

[0060] In an embodiment of the present invention, step A1 includes:

[0061] First, add water into the stirring kettle, start the stirring kettle, then add diamond, mix, and obtain a diamond solution.

[0062] The technical solution of the present invention selects to add water first, and then slowly add diamonds into the water to avoid agglomeration of micron diamonds caused by too fast addition. When adding diamonds, they can be added in multiple batches.

[0063] In an embodiment of the present invention, step A2 includes:

[0064] The diamond solution, the dispersant and the suspending agent are mixed in a stirring tank to obtain a mixed solution; wherein:

[0065] The frequency of the stirring kettle is 25 to 35 Hz;

[0066] The stirring time of the stirring tank is 20 to 40 minutes.

[0067] The technical solution of the present invention selects to mix the diamond solution, dispersant and suspending agent at a higher frequency, and sets the frequency and stirring time of the stirring kettle within the above range to ensure that the suspending agent is fully dissolved and effective. If it is lower than the above range, the mixed solution will not be fully stirred, affecting the suspension effect; if it is higher than the above range, the viscosity of the suspending agent will change.

[0068] The present invention provides a rough grinding method for a diamond substrate, comprising the following steps:

[0069] B1. Providing a diamond substrate;

[0070] B2, applying a rough grinding liquid on the diamond substrate, and performing rough grinding to obtain a rough ground diamond substrate;

[0071] Wherein, the rough grinding liquid is the rough grinding liquid for diamond substrate described in the above technical solution or the rough grinding liquid prepared by the preparation method of the rough grinding liquid for diamond substrate described in the above technical solution.

[0072] The rough grinding liquid provided by the present invention does not require a special grinding process, and can be carried out according to a conventional grinding process. In an embodiment of the present invention, the grinding is carried out in a 9B double-sided grinding machine, and the process parameters of the grinding are: the polishing pressure is 100-200g / cm 2 , rotation speed 20-50rpm, flow rate 100-300mL / min, and grinding disc temperature 20-30℃.

[0073] In an embodiment of the present invention, in step B2, the rough grinding rate is 10-12 μm / h. The technical solution of the present invention can effectively improve the polishing rate of the diamond substrate and ensure high-quality polishing effect by selecting diamond with a particle size of 10 μm to 50 μm as abrasive and selecting specific suspending agents and dispersants.

[0074] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0075] In the following examples, the D50 of the diamond is 20 μm.

[0076] Example 1

[0077] A rough grinding liquid for a diamond substrate comprises 1 part of diamond, 0.4 parts of anhydrous sodium metasilicate, 0.3 parts of xanthan gum, 3 parts of sodium hydroxide and 96.5 parts of water.

[0078] Example 2

[0079] A rough grinding liquid for a diamond substrate comprises 0.7 parts of diamond, 0.2 parts of sodium pyrophosphate, 0.5 parts of carbomer, 4 parts of pH potassium hydroxide and 94.6 parts of water.

[0080] Example 3

[0081] A rough grinding liquid for a diamond substrate comprises 1.2 parts of diamond, 0.5 parts of sodium pyrophosphate, 0.5 parts of carbomer, 5 parts of potassium hydroxide and 92.8 parts of water.

[0082] Example 4

[0083] A method for preparing a rough grinding liquid for a diamond substrate comprises the following steps:

[0084] (1) Add 96.5 parts of water to a stirring kettle, set the frequency of the stirring kettle to 20 Hz, start the stirring kettle, add 1 part of micron diamond, stir for 30 minutes, and obtain a diamond solution;

[0085] (2) adding 0.4 parts of anhydrous sodium metasilicate and 0.3 parts of xanthan gum to the diamond solution of step (1), increasing the frequency of the stirred tank to 30 Hz, and stirring for 30 minutes to obtain a mixed solution;

[0086] (3) adding sodium hydroxide to the mixed solution of step (2) to adjust the pH value of the system to within the range of 7 to 9, thereby obtaining the coarse grinding solution for diamond substrates.

[0087] Comparative Example 1

[0088] Compared with Example 1, the difference is that xanthan gum is replaced by sodium carboxymethyl cellulose.

[0089] Comparative Example 2

[0090] Compared with Example 1, the difference is that anhydrous sodium metasilicate is replaced by BYK-154.

[0091] Comparative Example 3

[0092] Compared with Example 1, the difference is that xanthan gum is replaced by sodium carboxymethyl cellulose, and anhydrous sodium metasilicate is replaced by BYK-154.

[0093] Comparative Example 4

[0094] Compared with Example 1, the difference is that the particle size of diamond is 5 μm.

[0095] Comparative Example 5

[0096] Compared with Example 1, the difference is that the particle size of diamond is 100 μm.

[0097] Performance Testing

[0098] The viscosity of the coarse grinding liquids of Examples 1-4 and Comparative Examples 1-5 was tested using a viscosity tester. The test results are shown in Table 1.

[0099] The rough grinding liquids of Examples 1-4 and Comparative Examples 1-5 were used to rough grind the diamond substrate. After rough grinding, the diamond substrate was washed and dried, and then the grinding rate, surface roughness and total thickness deviation were measured. The process parameters and test methods for rough grinding are as follows:

[0100] Rough grinding: Grinding in a 9B double-sided grinder, the process parameters are polishing pressure of 150g / cm 2 , rotation speed 40rpm, flow rate 200mL / min, and grinding disk temperature 25℃.

[0101] Testing method of grinding rate: Use analytical balance to test the mass of diamond substrate. The calculation formula of grinding rate is as follows: grinding rate = △m*10000 / (ρ*s*t), where △m (g) is the weight change of the workpiece during rough grinding, ρ is the density of diamond substrate (ρ=3.52g / cm2), s is the surface area of ​​the workpiece, and t is the polishing time. The test results are shown in Table 1.

[0102] Surface roughness test method: Use white light interferometer to test the surface roughness. The test results are shown in Table 1.

[0103] Total thickness deviation (TTV) test method: Use a micrometer to test the thickness of the diamond substrate. The thickness difference between the thickest point and the thinnest point is TTV. The test results are shown in Table 1.

[0104] Table 1 Performance test of the coarse grinding liquid of Examples 1-4 and Comparative Examples 1-5

[0105]

[0106]

[0107] As can be seen from Table 1, the grinding rate, surface roughness and total thickness deviation test results of the rough grinding fluid of Example 1 are better than those of Comparative Examples 1-3, and the comprehensive performance of the rough grinding fluids of Examples 1-4 is better, indicating that the rough grinding fluid provided by the present invention can take into account both the grinding rate and the processing effect, can effectively improve the grinding rate, and reduce the surface roughness and TTV of the diamond substrate.

[0108] It can also be seen from Table 1 that, when the coarse grinding liquid of Comparative Example 4 is used for grinding, although a lower surface roughness and TTV can be obtained, the grinding rate is low; when the coarse grinding liquid of Comparative Example 5 is used for grinding, although the grinding rate is fast, the test results of surface roughness and TTV become worse.

[0109] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the technical concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A rough grinding liquid for a diamond substrate, characterized in that: The invention comprises the following components in parts by weight: 0.5 to 1.5 parts of diamond, 0.1 to 1 parts of dispersant, 1 to 5 parts of pH regulator, 0.1 to 1 parts of suspending agent, and 88 to 98 parts of water; wherein: The D50 of the diamond is 10 μm to 50 μm; The suspending agent comprises at least one of xanthan gum, carbomer, sodium polyacrylate and bentonite; The dispersant includes at least one of polymaleic anhydride, sodium pyrophosphate, anhydrous sodium metasilicate and polyacrylamide.

2. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine and ammonia water.

3. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The pH value of the rough grinding liquid for diamond substrate is 7-9.

4. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The viscosity of the rough grinding liquid for diamond substrate is 1500-3000 mPa·s.

5. A method for preparing a rough grinding liquid for a diamond substrate according to any one of claims 1 to 4, characterized in that: The following steps are involved: A1. Mix diamond and water to obtain a diamond solution; A2, mixing the diamond solution, the dispersant and the suspending agent to obtain a mixed solution; A3. Adding a pH regulator to the mixed solution to obtain the rough grinding solution for the diamond substrate.

6. The method for preparing a rough grinding liquid for a diamond substrate according to claim 5, characterized in that: The step A1 comprises: Diamond and water are mixed in a stirred tank to obtain a diamond solution; wherein: The frequency of the stirring kettle is 15 to 20 Hz; and / or, The stirring time of the stirring tank is 20 to 40 minutes.

7. The method for preparing a rough grinding liquid for a diamond substrate according to claim 6, characterized in that: The step A1 comprises: First, add water into the stirring kettle, start the stirring kettle, then add diamond, mix, and obtain a diamond solution.

8. The method for preparing a rough grinding liquid for a diamond substrate according to claim 5, characterized in that: The step A2 comprises: The diamond solution, the dispersant and the suspending agent are mixed in a stirring tank to obtain a mixed solution; wherein: The frequency of the stirring kettle is 25 to 35 Hz; and / or, The stirring time of the stirring tank is 20 to 40 minutes.

9. A method for rough grinding of a diamond substrate, characterized in that: The following steps are involved: B1. Providing a diamond substrate; B2, applying a rough grinding liquid on the diamond substrate, and performing rough grinding to obtain a rough ground diamond substrate; Wherein, the rough grinding liquid is the rough grinding liquid for diamond substrate according to any one of claims 1 to 4 or the rough grinding liquid prepared by the preparation method of the rough grinding liquid for diamond substrate according to any one of claims 5 to 8.

10. The rough grinding method of a diamond substrate according to claim 9, characterized in that: In the step B2, the rough grinding rate is 10-12 μm / h.

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