Large-size silicon wafer diamond wire cutting fluid, preparation method and use thereof

Abstract

The present application discloses a large-size silicon wafer diamond wire cutting fluid, a preparation method and use thereof. The cutting fluid includes a wetting agent, a penetrant, a dispersant and deionized water, and the dispersant is a block copolymer polystyrene-polylactic acid. The present application adopts a dispersant with a comb-like shape to improve the dispersibility of silicon powder generated by cutting silicon wafers, effectively prevent silicon powder agglomeration, and at the same time weaken the adhesion of silicon powder on the silicon wafer, making it easier to be washed away by the cutting fluid; in addition, the dispersant also has a wetting effect on the silicon wafer. When used together with the wetting agent, it can significantly improve the wettability of the cutting fluid system, enhance the cutting ability of the cutting fluid, and reduce problems such as line marks and overcutting.

Description

Technical Field

[0001] The present application belongs to the field of silicon wafer cutting technology, and specifically relates to a large-size silicon wafer diamond wire cutting fluid, a preparation method thereof, and uses thereof. Background Art

[0002] Silicon wafer cutting is primarily based on diamond wire cutting, which offers advantages such as high efficiency, low cost, and environmental friendliness. Silicon wafers are hard materials, and the diamond wire cutting process generates significant heat and wear. Consequently, existing diamond wire cutting fluids for large-size silicon wafers still suffer from issues such as contamination, line marks, and total thickness variation (TTV). Summary of the Invention

[0003] Purpose of application: This application provides a large-size silicon wafer diamond wire cutting fluid, its preparation method and use, which is used for cutting large-size silicon wafers, provides good cutting force, and improves cutting efficiency.

[0004] Technical solution: The present application discloses a large-size silicon wafer diamond wire cutting fluid, which comprises the following components in parts by mass:

[0005]

[0006] Wherein, the dispersant is a block copolymer polystyrene-polylactic acid.

[0007] In some embodiments, the block copolymer polystyrene-polylactic acid has the following structural formula:

[0008]

[0009] Wherein, m represents the degree of polymerization of polystyrene, n represents the degree of polymerization of polylactic acid, and m:n=(0.2-0.5):(0.1-0.3).

[0010] In some embodiments, the block copolymer polystyrene-polylactic acid satisfies at least one of the following characteristics:

[0011] 1) m is selected from an integer of 20-50, and n is selected from an integer of 10-30;

[0012] 2) The average molecular weight is 3500 to 10000.

[0013] In some embodiments, the wetting agent is fatty alcohol polyoxyethylene ether.

[0014] In some embodiments, the wetting agent has the chemical formula RO(CH2CH2O) a H; wherein R is selected from C7-C 14 a represents the addition number of ethylene oxide groups, a is selected from an integer of 4-18.

[0015] In some embodiments, the penetrant is selected from at least one of propylene glycol, isohexylene glycol, PEG200, PEG400, and PEG600.

[0016] In some embodiments, the penetrant consists of PEG400 and isohexylene glycol; wherein the mass ratio of the PEG400 to the isohexylene glycol is (1-10):1.

[0017] In some embodiments, the present application further provides a method for preparing a large-size silicon wafer diamond wire cutting fluid, comprising the following steps:

[0018] Weigh corresponding parts by mass of a wetting agent, a penetrant, a dispersant and deionized water, mix them, stir them at 20-45° C. for 2-6 hours until they are completely dissolved, let them stand, and filter them to obtain a large-size silicon wafer diamond wire cutting fluid.

[0019] In some embodiments, the present application also provides a use of a large-size silicon wafer diamond wire cutting fluid in solar silicon wafer cutting.

[0020] In some embodiments, the size of the solar silicon wafer is 182-210 mm.

[0021] Beneficial effects: Compared with the prior art, the large-size silicon wafer diamond wire cutting fluid of the present application includes a wetting agent, a penetrant, a dispersant and deionized water, and the dispersant is a block copolymer polystyrene-polylactic acid. The present application adopts a dispersant with a comb-like shape to improve the dispersibility of silicon powder generated by cutting silicon wafers, effectively prevent silicon powder from agglomerating, and at the same time weaken the adhesion of silicon powder on the silicon wafer, making it easier to be washed away by the cutting fluid; in addition, the dispersant also has a wetting effect on the silicon wafer. When used together with the wetting agent, it can significantly improve the wettability of the cutting fluid system, enhance the cutting ability of the cutting fluid, and reduce problems such as line marks and over-cutting.

[0022] It can be understood that compared with the prior art, the preparation method of large-size silicon wafer diamond wire cutting fluid and the use of large-size silicon wafer diamond wire cutting fluid provided in the embodiments of the present application have all the technical features and beneficial effects of the above-mentioned cutting fluid, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0024] Figure 1 This is a comparison of the silicon wafers cut and cleaned using the cutting fluids of Example 1 and Comparative Example 2 of the present application;

[0025] Figure 2 This is the particle size distribution of silicon powder produced by cutting Example 1 and Comparative Examples 1-3 of the present application. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0027] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly specified and specifically limited. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features.

[0028] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0029] The applicant has discovered that with the continuous development and maturity of solar photovoltaic industry technology, the demand for silicon wafers is growing rapidly. Slicing is the first step in silicon wafer processing, and silicon wafers account for 30-40% of the cost of solar photovoltaic modules. Therefore, improvements in silicon wafer technology are of great significance for reducing module costs. In recent years, silicon wafer size has been continuously optimized, with a variety of sizes appearing, including 158.75mm, 160mm+, 182mm, and 210mm. Larger and thinner silicon wafers have become the mainstream technology trend, not only effectively reducing costs but also maximizing module efficiency. Diamond wire cutting is the main method for cutting solar silicon wafers, which offers advantages such as high efficiency, low cost, and environmental protection. Silicon wafers are a hard material, and the diamond wire cutting process generates a large amount of heat and wear. As the size and thinness of silicon wafers increase, higher performance requirements are placed on cutting fluids to adapt to the cutting of large-sized silicon wafers and improve yield. However, existing diamond wire cutting fluids for large-sized silicon wafers still have problems such as contamination, line marks, and TTV. Therefore, it is necessary to develop a cutting fluid that is safe, environmentally friendly, clean, highly wettable and dispersible, and non-corrosive to solar silicon wafers, which can be used for cutting large-size silicon wafers.

[0030] The present invention provides a large-size silicon wafer diamond wire cutting fluid, which comprises the following components in parts by mass:

[0031]

[0032] Wherein, the dispersant is a block copolymer polystyrene-polylactic acid.

[0033] It is understood that the block copolymer polystyrene-polylactic acid can form an adsorption layer on the surface of solid particles, increasing the surface charge of the solid particles and enhancing the interparticle reaction force that forms a steric barrier. This copolymer can tightly and firmly bind to the surface of silicon powder, achieving highly efficient coverage, while also acting as a steric barrier, providing a steric stabilization barrier. Therefore, using a cutting fluid containing this dispersant can exhibit high dispersibility. During silicon wafer cutting, it can significantly disperse and wet the silicon powder produced by cutting, effectively preventing silicon powder from agglomerating and flocculating, adhering to the silicon wafer surface and becoming difficult to clean, thereby significantly reducing the silicon wafer fouling rate. This copolymer can adsorb to the surface of silicon powder, forming a bilayer structure on the silicon powder surface. The outer polar end has a strong affinity for water, increasing the degree of water wetting of the solid particles and making the surface of the agglomerated solid particles easier to wet, thereby enhancing the wetting effect of the wetting agent.

[0034] Furthermore, when polystyrene-polylactic acid is added to the cutting fluid, due to the characteristics of its block structure, the polystyrene and polylactic acid form a microphase-separated structure in the cutting fluid. The polystyrene blocks form a granular structure in the cutting fluid, while the polylactic acid blocks form a coating on the surface of the particles. This microphase-separated structure enables polystyrene-polylactic acid to effectively disperse and stabilize solid particles or suspended matter in the cutting fluid. The granular structure of the polystyrene blocks can encapsulate and disperse the solid particles, preventing their aggregation and sedimentation. At the same time, the coating of the polylactic acid blocks provides interfacial activity, making the solid particles more compatible with the liquid phase in the cutting fluid, reducing the interaction forces between the particles, and further improving the dispersion effect. In addition, by using polystyrene-polylactic acid as a dispersant, the solid particles in the cutting fluid can be evenly dispersed in the liquid phase, preventing particle aggregation and sedimentation, thereby improving the stability of the cutting fluid and the cutting effect. In addition, polystyrene-polylactic acid as a dispersant can also provide wettability and lubricity, improving the contact and friction performance between the cutting fluid and the silicon wafer.

[0035] In some embodiments, the cutting fluid further preferably comprises, by weight, 15-20 parts of a wetting agent, 25-30 parts of a penetrant, 0.5-1 parts of a dispersant, and 40-50 parts of deionized water.

[0036] In some embodiments, the block copolymer polystyrene-polylactic acid has the following structure:

[0037]

[0038] Wherein, m represents the degree of polymerization of polystyrene, n represents the degree of polymerization of polylactic acid, and m:n=(0.2-0.5):(0.1-0.3).

[0039] It is understood that the block copolymer polystyrene-polylactic acid can be represented as PS-b-PLA, and its specific preparation method can be synthesized by nitroxide free radical polymerization. For example, nitroxide free radical polymerization was used to initiate styrene polymerization at above 120°C using a HTEMPO / AIBN initiation system, effectively controlling styrene and preparing polystyrene (PS-OH) containing terminal hydroxyl groups. Subsequently, using PS-OH as a macroinitiator, a coordination-insertion ring-opening polymerization mechanism was used to successfully synthesize the block copolymer polystyrene-polylactic acid, catalyzed by stannous octoate, by initiating lactide ring-opening polymerization. The ratio [LA] / [PS-OH] is linearly related to the molecular weight of the block copolymer, indicating that the PLA block is tunable.

[0040] Furthermore, when the block copolymer polystyrene-polylactic acid satisfies the ratio m:n = (0.2-0.5):(0.1-0.3), the dispersant's performance can be adjusted by adjusting the range of m and n. The preferred range of m:n is 0.3:0.2 or 0.4:0.1. Within this preferred block ratio range, a moderate content of polylactic acid can achieve good dispersion and stability. Different ratios can be adapted to different dispersion systems and application requirements.

[0041] In some embodiments, m is selected from an integer of 20-50, and n is selected from an integer of 10-30; for example, m can be any one of 20, 30, 40, 50 or an integer between any two values; n can be any one of 10, 20, 30 or an integer between any two values.

[0042] In some embodiments, the average molecular weight of the block copolymer polystyrene-polylactic acid is 3500 to 10000, for example, any one of 3500, 4000, 5000, 6000, 7000, 8000, 9000, and 10000, or a range between any two of these values.

[0043] In some embodiments, the wetting agent is a fatty alcohol polyoxyethylene ether, which is a type of nonionic surfactant formed by combining fatty alcohols and polyoxyethylene ethers. Fatty alcohols are alcohol compounds obtained by reducing fatty acids, while polyoxyethylene ethers are polymers obtained by reacting ethylene glycol and ethylene oxide. Fatty alcohol polyoxyethylene ethers have a high hydrophilicity and can interact with water molecules and form hydrogen bonds. This enables them to form a thin and uniform wetting film on the surface of the liquid, reducing the surface tension of the liquid and making it easier to spread and penetrate the solid surface. Fatty alcohol polyoxyethylene ethers can interact with the solid surface, making it easier for the liquid to spread evenly on the solid surface, reducing the contact angle and improving the wetting properties. Fatty alcohol polyoxyethylene ethers have good solubility in water and many organic solvents, which makes them compatible with the other ingredients in the wetting agent and provides a uniform wetting effect. Fatty alcohol polyoxyethylene ethers have a certain degree of permeability and can penetrate into the tiny pores on the solid surface, improving the wetting effect.

[0044] In some embodiments, the wetting agent has the formula RO(CH2CH2O) a H; wherein R is selected from C7-C 14 a represents the addition number of ethylene oxide groups, a is selected from an integer of 4-18.

[0045] Furthermore, the ether bonds in this wetting agent's molecules are resistant to acid and alkali damage, resulting in high stability, good water solubility, electrolyte resistance, biodegradability, and minimal foaming. The ethylene oxide in its structure modifies its polymerization number, thereby reducing surface tension and improving wettability. During the silicon wafer dicing process, it simultaneously wets the silicon wafer surface and silicon powder.

[0046] In certain embodiments, the penetrant is selected from at least one of propylene glycol, isohexylene glycol, PEG200, PEG400, and PEG600. It is understandable that propylene glycol, isohexylene glycol, and PEG series polyethylene glycols (such as PEG200, PEG400, and PEG600) all have good permeability, and they can penetrate into solid materials, improve the softness and plasticity of the material, and promote the penetration and diffusion of other components. In addition, the penetrant not only has wetting permeability, but also its high wettability can slow down the volatilization of moisture on the silicon chip surface. During the cutting process, the protective film formed by the wetting agent on the silicon chip surface is kept for a longer time, effectively reducing scratches and line marks, and making the silicon powder adhered to the silicon chip surface easier to rinse clean.

[0047] In some embodiments, fatty alcohol polyoxyethylene ether and propylene glycol, isohexylene glycol, and PEG series polyethylene glycols all have good moisturizing properties. They can absorb moisture and maintain a moist state, providing a long-lasting moisturizing effect. The interaction of their structures and properties may enhance each other's functions and improve the overall performance of the product. This synergistic effect may include enhanced permeability, improved solubility and dispersibility, enhanced moisturizing properties, etc.

[0048] In some embodiments, the penetrant is composed of PEG400 and isohexylene glycol, wherein the mass ratio of PEG400 to isohexylene glycol is (1-10):1. Further preferably, the mass ratio of PEG400 to isohexylene glycol is (3-8):1; further preferably, the mass ratio of PEG400 to isohexylene glycol is 6:1.

[0049] It is understandable that using PEG400 and isohexanediol as penetrants helps improve the water solubility of the dispersant, making it more soluble in water and having a more significant dispersing effect, while also improving the stability of the cutting fluid. Both PEG400 and isohexanediol have excellent penetrating properties. They can penetrate into solid materials, improving the softness and plasticity of the materials and promoting the penetration and diffusion of other ingredients. The combined use of PEG400 and isohexanediol can further enhance the penetration effect. In addition, they are compatible with other ingredients and provide a uniform dissolution and dispersion effect. By working together, they can improve the solubility and dispersibility of the ingredients and enhance the stability of the product.

[0050] In some embodiments, a method for preparing a large-size silicon wafer diamond wire cutting fluid is provided, comprising the following steps:

[0051] Weigh corresponding parts by mass of a wetting agent, a penetrant, a dispersant and deionized water, mix them, stir them at 20-45° C. for 2-6 hours until they are completely dissolved, let them stand, and filter them to obtain a large-size silicon wafer diamond wire cutting fluid.

[0052] In some embodiments, the specific preparation method comprises the following steps:

[0053] Step 1: Add half of deionized water to the stirred tank and start stirring;

[0054] Step 2: Add wetting agent, penetrant, and dispersant and continue stirring;

[0055] Step 3: Add the remaining half of the deionized water and continue stirring;

[0056] Step 4: Control the temperature of the reactor at 20-45°C and stir for 4 hours until it is completely dissolved;

[0057] Step 5: Stop stirring and let it sit for 4-8 hours;

[0058] Step 6: Filter with a filter bag to obtain large-size silicon wafer diamond wire cutting fluid.

[0059] In some embodiments, the temperature of the stirring after mixing can be any one of 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, or a range between any two of these values.

[0060] In some embodiments, the diamond wire cutting fluid is used to cut solar silicon wafers, particularly for large-size solar silicon wafers ranging from 182 mm to 210 mm. The cutting fluid provided in the embodiments of this application has excellent application prospects and potential for large-scale industrialization in the field of solar silicon wafer cutting.

[0061] Example 1

[0062] Provided is a large-size silicon wafer diamond wire cutting fluid, comprising: 16 parts of a wetting agent, 28 parts of a penetrant, 0.7 parts of a dispersant and 45 parts of deionized water; wherein the chemical formula of the wetting agent is C 12 H 25 O(CH2CH2O) 11 H; the penetrant is composed of PEG400 and isohexylene glycol in a mass ratio of 6:1; the dispersant is a block copolymer polystyrene-polylactic acid, the structural formula of the block copolymer polystyrene-polylactic acid is shown above, wherein m:n=0.3:0.2, and the molecular weight is 5925.

[0063] The preparation method of the cutting fluid is as follows: at room temperature (25°C), add half of the deionized water into the stirring kettle and start stirring; then add the wetting agent, penetrant, and dispersant and continue stirring; then add the remaining half of the deionized water and continue stirring; control the temperature of the reaction stirring kettle at 30°C, stir for 4 hours until it is completely dissolved; stop stirring and let it stand for 5 hours; then filter with a filter bag to obtain large-size silicon wafer diamond wire cutting fluid.

[0064] Example 2

[0065] Provided is a large-size silicon wafer diamond wire cutting fluid, comprising: 10 parts wetting agent, 35 parts penetrant, 0.1 parts dispersant and 40 parts deionized water; wherein the chemical formula of the wetting agent is C7H 15 O(CH2CH2O) 18 H; the penetrant is composed of PEG200 and isohexylene glycol in a mass ratio of 1:1; the dispersant is a block copolymer polystyrene-polylactic acid, the structural formula of the block copolymer polystyrene-polylactic acid is shown above, wherein m:n=0.4:0.1, and the molecular weight is 5685.

[0066] The preparation method of the cutting fluid is as follows: at room temperature (25°C), add half of the deionized water into a stirring tank and start stirring; then add a wetting agent, a penetrant, and a dispersant and continue stirring; then add the remaining half of the deionized water and continue stirring; control the temperature of the reaction stirring tank at 40°C, stir for 6 hours until it is completely dissolved; stop stirring, let it stand for 4 hours; then filter with a filter bag to obtain the solar silicon wafer diamond wire cutting fluid.

[0067] Example 3

[0068] Provided is a large-size silicon wafer diamond wire cutting fluid, comprising: 20 parts of wetting agent, 20 parts of penetrant, 2 parts of dispersant and 60 parts of deionized water; wherein the chemical formula of the wetting agent is C 14 H 29 O(CH2CH2O)4H; the penetrant is composed of PEG600 and isohexanediol in a mass ratio of 10:1; the dispersant is a block copolymer polystyrene-polylactic acid, the structural formula of the block copolymer polystyrene-polylactic acid is shown above, wherein m:n=0.2:0.3 and the molecular weight is 6165.

[0069] The preparation method of the cutting fluid is as follows: at room temperature (25°C), add half of the deionized water into the stirring tank and start stirring; then add the wetting agent, penetrant, and dispersant and continue stirring; then add the remaining half of the deionized water and continue stirring; control the temperature of the reaction stirring tank at 20°C, stir for 2 hours until it is completely dissolved; stop stirring and let it stand for 8 hours; then filter with a filter bag to obtain large-size silicon wafer diamond wire cutting fluid.

[0070] Example 4

[0071] Provided is a large-size silicon wafer diamond wire cutting fluid, comprising: 15 parts of a wetting agent, 30 parts of a penetrant, 0.5 parts of a dispersant and 45 parts of deionized water; wherein the chemical formula of the wetting agent is C 10 H 21 O(CH2CH2O)8H; the penetrant is propylene glycol; the dispersant is block copolymer polystyrene-polylactic acid, the structural formula of the block copolymer polystyrene-polylactic acid is shown above, wherein m:n=0.5:0.1, and the molecular weight is 6725.

[0072] The preparation method of the cutting fluid is as follows: at room temperature (25°C), add half of the deionized water into the stirring kettle and start stirring; then add the wetting agent, penetrant, and dispersant and continue stirring; then add the remaining half of the deionized water and continue stirring; control the temperature of the reaction stirring kettle at 45°C, stir for 4 hours until it is completely dissolved; stop stirring and let it stand for 6 hours; then filter with a filter bag to obtain large-size silicon wafer diamond wire cutting fluid.

[0073] Example 5

[0074] Provided is a large-size silicon wafer diamond wire cutting fluid, comprising: 20 parts of wetting agent, 25 parts of penetrant, 1 part of dispersant and 50 parts of deionized water; wherein the chemical formula of the wetting agent is C 14 H 27 O(CH2CH2O) 15 H; the penetrant is isohexylene glycol; the dispersant is a block copolymer polystyrene-polylactic acid, the structural formula of the block copolymer polystyrene-polylactic acid is shown above, wherein m:n=0.4:0.2, and the molecular weight is 6985.

[0075] The preparation method of the cutting fluid is as follows: at room temperature (25°C), add half of the deionized water into the stirring kettle and start stirring; then add the wetting agent, penetrant, and dispersant and continue stirring; then add the remaining half of the deionized water and continue stirring; control the temperature of the reaction stirring kettle at 35°C, stir for 3 hours until it is completely dissolved; stop stirring and let it stand for 7 hours; then filter with a filter bag to obtain large-size silicon wafer diamond wire cutting fluid.

[0076] Comparative Example 1

[0077] Provided is a cutting fluid, which comprises components of: 45 parts of deionized water, 25 parts of polyethylene glycol, 7.5 parts of ethylene glycol, 7.5 parts of propylene glycol, 1 part of citric acid, and 0.5 part of oxalic acid; the cutting fluid is a traditional cutting fluid.

[0078] Comparative Example 2

[0079] A cutting fluid is provided, the specific composition of which is similar to that of Example 1, except that Comparative Example 2 does not contain a dispersant.

[0080] Comparative Example 3

[0081] A cutting fluid is provided, the specific composition of which is similar to that of Example 1, except that Comparative Example 3 does not contain the polystyrene-polylactic acid in Example 1, but uses sodium methylene bis(methyl naphthalene sulfonate as a substitute.

[0082] See also Figure 1 ,in, Figure 1 Middle A is a picture of the silicon wafer before cleaning; Figure 1 B is a picture of a silicon wafer cut with the cutting fluid of Example 1 after cleaning; Figure 1 Figure C is a picture of a silicon wafer cut and cleaned using the cutting fluid of Comparative Example 2. Figure 1 It can be seen that compared with the surface state of the silicon wafer before cleaning, after the silicon wafer is cut and cleaned using the cutting fluid of Example 1 of the present application, the surface of the silicon wafer has no marks and the degree of dirtiness is low. This shows that the cutting fluid provided by Example 1 of the present application can effectively prevent the agglomeration and flocculation of silicon powder, avoid the adhesion of silicon powder to the surface of the silicon wafer, improve the cleaning effect and significantly reduce the dirtiness rate of the silicon wafer.

[0083] Furthermore, the cutting fluids of Examples 1-5 and Comparative Examples 1-3 were used to cut 210 mm silicon wafers, respectively. The same cutting equipment was used, and the thickness of the cut silicon wafers was measured at five points selected by a sorting machine. The results are shown in Table 1 below.

[0084] Table 1

[0085]

[0086]

[0087] As can be seen from Table 1, the diamond wire cutting fluid provided in the embodiments of the present application can be used to cut solar silicon wafers, and is particularly suitable for cutting solar silicon wafers of large size of 182 mm to 210 mm and thickness of 150 μm.

[0088] Dispersion test:

[0089] (1) Particle size test

[0090] The particle sizes of silicon powder produced by cutting in the cutting fluids of Examples 1-5 and Comparative Examples 1-3 were measured respectively. Figure 2 Compared with Comparative Examples 1-3, it can be seen that the silicon powder in Example 1 has no agglomeration and the particle size distribution is more concentrated.

[0091] (2) Zeta potential test

[0092] The zeta potential of the silicon powder produced by cutting in the cutting fluids of Examples 1-5 and Comparative Examples 1-3 was measured four times to obtain the average value. The specific results are shown in Table 2 below.

[0093] Table 2

[0094]

[0095]

[0096] As can be seen from Table 2, the absolute values of the Zeta potential of Examples 1-5 are higher, indicating that the cutting fluids of Examples 1-5 of the present application have better dispersion stability for silicon powder than those of Comparative Examples 1-3.

[0097] Under the same cutting parameter conditions (cutting 210 mm silicon wafers), the performance of the solar silicon wafer diamond wire cutting fluid prepared in the embodiment was compared with the diamond wire cutting fluid of the comparative example. The specific results are shown in Table 3 below.

[0098] Table 3

[0099] Grade A yield Grade B yield Line marks TTVμm Dirt rate Example 1 96.8％ 98.7％ 2.1％ 1.50 1.5％ Example 2 96.5％ 98.5％ 2.3％ 2.68 1.6％ Example 3 96.6％ 98.4％ 2.4％ 2.33 1.8％ Example 4 96.3％ 98.1％ 2.7％ 2.59 1.9％ Example 5 96.2％ 98.2％ 2.5％ 1.94 2.1％ Comparative Example 1 91.7％ 93.9％ 5.7％ 13.16 6.9％ Comparative Example 2 92.1％ 94.2％ 5.5％ 11.62 6.1％ Comparative Example 3 92.3％ 94.6％ 5.4％ 9.53 5.4％

[0100] The A-grade yield rate is the ratio of wafers that fully meet shipping standards to the total number of wafers cut. The B-grade yield rate refers to the ratio of wafers that fully meet shipping standards and wafers with minor defects that do not affect shipment to the total number of wafers. Line marks are mostly scratches, mainly caused by silicon powder agglomerating between the steel wire and the silicon wafer, unable to escape. TTV is calculated by measuring the maximum and minimum thicknesses of the silicon wafer after cutting using a thickness gauge. The difference between the two is the TTV. The dirt rate refers to the ratio of wafers with obvious silicon powder agglomeration, which is difficult to rinse clean, to the total number of wafers.

[0101] As can be seen from Table 3, the silicon wafer yield obtained by the cutting fluid of the embodiment of the present application is higher, the line marks are fewer, and the dirt rate is lower. It is a safe, environmentally friendly, clean, highly wettable and dispersible diamond wire cutting fluid that does not corrode solar silicon wafers. It can be used in the cutting process of large-size silicon wafers, provides good cutting force, and improves cutting efficiency. It has very good application prospects and large-scale industrial promotion potential in the field of solar silicon wafer cutting.

[0102] The above is a detailed introduction to a large-size silicon wafer diamond wire cutting fluid, its preparation method and use provided in the embodiments of the present application. Specific examples are used in this application to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application; ordinary technicians in this field should understand that: they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A large-size silicon wafer diamond wire cutting fluid, characterized in that: The cutting fluid includes the following components in parts by mass: Wherein, the dispersant is a block copolymer polystyrene-polylactic acid; The block copolymer polystyrene-polylactic acid has the following structural formula: ； Wherein, m represents the degree of polymerization of polystyrene, n represents the degree of polymerization of polylactic acid, and m:n=(0.2-0.5):(0.1-0.3); The average molecular weight of the block copolymer polystyrene-polylactic acid is 3500-10000.

2. The large-size silicon wafer diamond wire cutting fluid according to claim 1, characterized in that: The block copolymer polystyrene-polylactic acid meets the following characteristics: m is selected from an integer of 20-50, and n is selected from an integer of 10-30.

3. The large-size silicon wafer diamond wire cutting fluid according to claim 1, characterized in that: The wetting agent is fatty alcohol polyoxyethylene ether.

4. The large-size silicon wafer diamond wire cutting fluid according to claim 3, characterized in that: The chemical formula of the wetting agent is RO(CH2CH2O) a H; wherein R is selected from C7-C 14 a represents the addition number of ethylene oxide groups, a is selected from an integer of 4-18.

5. The large-size silicon wafer diamond wire cutting fluid according to claim 1, characterized in that: The penetrant is selected from at least one of propylene glycol, isohexylene glycol, PEG200, PEG400, and PEG600.

6. The large-size silicon wafer diamond wire cutting fluid according to claim 5, characterized in that: The penetrant is composed of PEG400 and isohexylene glycol; wherein the mass ratio of the PEG400 to the isohexylene glycol is (1-10):

1.

7. A method for preparing a large-size silicon wafer diamond wire cutting fluid according to any one of claims 1 to 6, characterized in that: The following steps are involved: Weigh corresponding parts by mass of a wetting agent, a penetrant, a dispersant and deionized water, mix them, stir them at 20-45° C. for 2-6 hours until they are completely dissolved, let them stand, and filter them to obtain a large-size silicon wafer diamond wire cutting fluid.

8. Use of the large-size silicon wafer diamond wire cutting fluid according to any one of claims 1 to 6 in cutting solar silicon wafers.

9. The use according to claim 8, characterized in that The size of the solar silicon wafer is 182-210 mm.

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