Laser cutting protection liquid and preparation method thereof

Abstract

The invention discloses a laser cutting protection liquid and a preparation method thereof. The laser cutting protection liquid comprises a film-forming agent, polyol, an ultraviolet absorbent, an alcohol ether compound, a betaine type surfactant and ultrapure water. The laser cutting protection liquid provided by the invention is prepared from ultrapure water, does not have any polluting ion source, can improve the adsorption and anti-diffusion performance of a protection film on silicon chips generated in the cutting process, solves the problem that a chip is easily polluted, and can form a protection film which is good in uniformity and protection effect and is not easily influenced by a heat effect; and meanwhile, it is ensured that the protective film is easy to clean and not prone to being left on the surface of the wafer, and the clean machining requirement for laser cutting of the silicon wafer in the advanced manufacturing process is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser cutting protection liquid, and particularly relates to a laser cutting protection liquid and a preparation method thereof. BACKGROUND

[0002] In the field of chip manufacturing, with the continuous evolution of chip manufacturing process to 7 nm and below advanced nodes, the size of silicon wafers is continuously expanding to larger specifications such as 12 inches and 18 inches, and at the same time, the thickness and pitch of chip dies continue to be reduced. This series of technology upgrades has put forward more stringent requirements for the precision control, surface flatness and damage control of silicon wafer cutting. The traditional cutting technology has been difficult to adapt to the processing needs of advanced processes. Laser cutting technology has become a key technology for wafer dicing (i.e. accurately separating a whole wafer into individual chip dies) and silicon wafer precision cutting due to its non-contact processing and high resolution core advantages. The processing effect directly affects the yield of chip manufacturing and the final reliability of the device.

[0003] However, as a brittle semiconductor material, silicon wafers still face many technical problems to be solved during laser cutting: when high-energy laser beams act on the surface of silicon wafers, a heat-affected zone exceeding 10 μm is easily generated, which in turn causes micro-cracks, edge collapse and polyimide (PI) burning on the edge of the silicon wafer. These defects will continue to expand during subsequent packaging or use, thereby causing serious problems such as chip leakage and mechanical strength reduction. At the same time, silicon powder particles generated during the cutting process are easily attached to the wafer surface and cutting path. If not thoroughly cleaned, it will cause contamination of the chip electrode and significantly affect the bonding quality. In addition, during the cutting process of ultra-thin silicon wafers (thickness < 50 μm) used in some advanced packaging, warping deformation is easily generated due to thermal stress, further reducing the cutting yield and seriously restricting the large-scale production of advanced process chips.

[0004] To solve the above technical problems, the existing technology has tried to use water cooling assistance, adjust the laser pulse width and other process optimization methods, but the water cooling assistance method is easy to cause water stains to remain on the surface of the silicon wafer, and the inhibitory effect on micro-cracks is limited. Simply adjusting the process parameters is difficult to achieve effective damage control while ensuring processing efficiency. Therefore, it is urgent to develop a laser cutting protection liquid that is suitable for the material properties of silicon wafers and can accurately meet the clean environment requirements of chip manufacturing.

[0005] Chinese patent CN105489472A discloses a front dicing protective liquid and a wafer processing method using the protective liquid, the front dicing protective liquid comprising polyvinyl alcohol or denatured polyvinyl alcohol, an ultraviolet light absorber, and a solvent. Chinese patent CN115304967A provides a water-soluble wafer dicing protective liquid, a preparation method, a use, and a wafer dicing method using the same, the protective liquid also containing polyvinyl alcohol. However, the above-mentioned existing protective liquids still have obvious defects in actual application: firstly, the adsorption and diffusion prevention ability for silicon chips generated by cutting is insufficient, which easily causes chip electrode pollution; secondly, the uniformity of the protective film formed on the wafer surface is poor, resulting in poor protection and difficulty in effectively resisting the thermal influence and mechanical damage in the laser cutting process; thirdly, the formed protective film is difficult to clean and is easily left on the wafer surface, which adversely affects the subsequent packaging process, and finally affects the quality and yield of the chip product. SUMMARY

[0006] To solve the above technical problems, the purpose of the present application is to provide a laser dicing protective liquid and a preparation method thereof.

[0007] The above-mentioned purpose of the present application is achieved by the following technical solutions:

[0008] The present application provides a laser dicing protective liquid, the laser dicing protective liquid comprising a film-forming agent, a polyol, an ultraviolet absorber, an alcohol ether compound, a betaine surfactant, and ultrapure water;

[0009] The film-forming agent comprises polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA), and the weight average molecular weight (Mw) of the polyvinylpyrrolidone is 40-360 kDa;

[0010] The ultraviolet absorber is selected from one or more of 1H-benzo[d]imidazole-2-sulfonic acid, 1-benzyl-1H-benzimidazole-2-sulfonic acid, 1-propyl-1H-benzimidazole-2-sulfonic acid, and 4,5-dihydro-1H-imidazole-2-sulfonic acid;

[0011] The content of the film-forming agent in the laser dicing protective liquid is 5-15 wt%; the content of the polyol in the laser dicing protective liquid is 5-15 wt%; the content of the ultraviolet absorber in the laser dicing protective liquid is 0.01-0.05 wt%; the content of the alcohol ether compound in the laser dicing protective liquid is 40-80 wt%; and the content of the betaine surfactant in the laser dicing protective liquid is 100-500 ppm.

[0012] The laser cutting protection liquid prepared by the present application is prepared by ultrapure water and does not have any source of contaminating ions, can improve the adsorption and diffusion prevention performance of the protective film to the silicon chips generated in the cutting process, solve the problem that the chips are easily contaminated, can form a protective film with good uniformity, good protection effect and not easy to be affected by thermal effect, and further improve the cutting precision and speed, while ensuring that the protective film is easy to clean and not easy to remain on the wafer surface, and meets the clean processing needs of advanced process silicon laser cutting.

[0013] Further, the mass ratio of the polyvinylpyrrolidone and the polyvinyl alcohol is (4-6):1, preferably 5:1.

[0014] The polyvinylpyrrolidone (PVP) and the polyvinyl alcohol (PVA) are copolymerized to form a PVP-PVA copolymer system, which is used as a film former in the laser cutting protection liquid, and the core function is to uniformly cover the wafer surface through a spin coating process to form a protective film with excellent water solubility and excellent stability.

[0015] Further, the polyvinyl alcohol has a degree of polymerization of 1000-2000, preferably 1500.

[0016] Further, the polyvinyl alcohol has an alcoholysis degree of 75-85, preferably 80.

[0017] Further, the polyvinyl alcohol has a block distribution coefficient η <1.2.

[0018] Further, the polyhydric alcohol is selected from one or more of ethylene glycol, propylene glycol, glycerol, and butanetetrol.

[0019] The polyhydric alcohol can efficiently absorb the heat generated by the laser in the laser cutting process, significantly weaken the damage of the heat affected zone to the silicon wafer, and further improve the water solubility of the protective film, which is beneficial to subsequent cleaning.

[0020] The imidazole sulfonic acid compound contains both an imidazole group and a sulfonic acid group: the imidazole group can accurately capture the ultraviolet band energy in the laser to avoid damage to the silicon wafer and the PI layer caused by direct laser irradiation; the sulfonic acid group gives it good hydrophilicity, ensuring that it is uniformly dispersed in the protective liquid. Selecting 1H-benzo[d]imidazole-2-sulfonic acid and other imidazole sulfonic acid compounds as ultraviolet absorbers can accurately intercept the excess energy of the laser in the laser cutting process, effectively inhibit the damage to the non-target area caused by laser scattering, avoid the adverse effects of laser radiation on the silicon wafer and the surface PI layer, and further protect the cutting precision and chip integrity.

[0021] Further, the alcohol ether compound is selected from one or more of propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and propylene glycol propyl ether.

[0022] The alcohol-ether compound has both the hydrophilicity of alcohol and the hydrophobicity of ether, and can be used as a compatible solvent for each component to ensure that the film-forming agent, ultraviolet absorber, etc. are uniformly dispersed in the protective solution, avoiding stratification or precipitation.

[0023] Further, the betaine surfactant is selected from one or more of cocamidopropyl betaine, dodecyl ethoxy sulfobetaine, dodecyl hydroxypropyl sulfobetaine, and decyl hydroxypropyl sulfobetaine.

[0024] The betaine surfactant has a zwitterionic structure, and has the properties of both cations and anions: on the one hand, its hydrophilic group can interact with the film-forming agent molecules and the solvent to promote the uniform spreading of the film-forming agent on the wafer surface, reducing the number of missed points and the difference in film thickness; on the other hand, its charge characteristics can efficiently capture positive and negative charged silicon particles generated during cutting through electrostatic adsorption, preventing the diffusion and adhesion of silicon particles and reducing the risk of chip electrode contamination.

[0025] Further, the resistivity of the ultrapure water is greater than 18 MΩ·cm.

[0026] Further, the ultrapure water is the balance in the laser cutting protective solution.

[0027] The ultrapure water in the laser cutting protective solution is used as a balance component, and the other functional components (film-forming agent, polyol, ultraviolet absorber, alcohol-ether compound, betaine surfactant) are mixed in corresponding proportions, and then the ultrapure water is added to make up the total mass or total volume of the protective solution. The ultrapure water does not contain sources of contaminating ions, and can avoid introducing metal ions, soluble salts and other impurities into the protective solution, preventing problems such as chip leakage and electrode corrosion, and adapting to the clean environment requirements of chip manufacturing.

[0028] Preferably, the content of ultrapure water in the laser cutting protective solution is 1-30 wt%.

[0029] The present application also protects the preparation method of the above-mentioned laser cutting protective solution, which comprises the following steps: mixing the film-forming agent, polyol, ultraviolet absorber, alcohol-ether compound, betaine surfactant, and ultrapure water to obtain the laser cutting protective solution.

[0030] Further, the mixing temperature is 20-40 ℃.

[0031] Further, after mixing, the stirring speed is 400-600 rpm, and the stirring time is 1-3 h.

[0032] The above technical solutions of the present application have the following beneficial effects compared with the prior art:

[0033] The laser cutting protective liquid provided by the application has the following advantages: the film forming agent (PVP-PVA copolymer system) and the betaine surfactant have a significant synergistic effect, and the use of the two can greatly improve the film forming uniformity; the betaine surfactant can effectively promote the PVP-PVA copolymer film forming agent to uniformly spread and densely adhere on the wafer surface, and the use of a single PVP or PVA film forming component cannot achieve this effect; the imidazole sulfonic acid compound used as the ultraviolet absorber has a significantly better laser damage prevention performance than a single imidazole or sulfonic acid compound, and has a synergistic effect with the polyhydric alcohol; in the imidazole sulfonic acid compound, the imidazole structure endows the compound with organic solubility, the sulfonic acid group endows the compound with hydrophilicity, and the polyhydric alcohol can further strengthen the solubility and dispersibility of the compound in the protective liquid, so that the compound can fully play the core function of intercepting laser energy and inhibiting damage to non-target areas. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a physical picture of an 8-inch wafer after spin coating by the laser cutting protective liquid of Example 1.

[0035] Figure 2 It is a metallographic microscope observation picture of a commercial wafer after spin coating and laser cutting by the laser cutting protective liquid of Example 1.

[0036] Figure 3 It is a metallographic microscope observation picture of a commercial wafer after spin coating and laser cutting by the laser cutting protective liquid of Example 2. DETAILED DESCRIPTION

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0038] The application will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the application and implement it. The embodiments are not intended to limit the application.

[0039] In the following examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0040] Example 1

[0041] A laser cutting protective fluid comprising 10 wt% of a film former, 10 wt% of glycerol, 0.03 wt% of 1H-benzo[d]imidazole-2-sulfonic acid, 60 wt% of propylene glycol methyl ether, 300 ppm of dodecyl ethoxy sulfobetaine, and a balance of ultrapure water;

[0042] The film former is PVP (Mw = 40 kDa) and PVA, and the mass ratio of PVP to PVA is 5:1.

[0043] Example 2

[0044] A laser cutting protective fluid comprising 10 wt% of a film former, 10 wt% of glycerol, 0.03 wt% of 4,5-dihydro-1H-imidazole-2-sulfonic acid, 60 wt% of propylene glycol methyl ether, 300 ppm of decyl hydroxypropyl sulfobetaine, and a balance of ultrapure water;

[0045] The film former is PVP (Mw = 40 kDa) and PVA, and the mass ratio of PVP to PVA is 5:1.

[0046] Example 3

[0047] A laser cutting protective fluid comprising 10 wt% of a film former, 10 wt% of 1,2-propanediol, 0.03 wt% of 1H-benzo[d]imidazole-2-sulfonic acid, 60 wt% of dipropylene glycol methyl ether, 300 ppm of dodecyl ethoxy sulfobetaine, and a balance of ultrapure water;

[0048] The film former is PVP (Mw = 40 kDa) and PVA, and the mass ratio of PVP to PVA is 5:1.

[0049] Example 4

[0050] A laser cutting protective fluid comprising 15 wt% of a film former, 10 wt% of glycerol, 0.05 wt% of 1-propyl-1H-benzimidazole-2-sulfonic acid, 40 wt% of tripropylene glycol methyl ether, 300 ppm of cocamidopropyl betaine, and a balance of ultrapure water;

[0051] The film former is PVP (Mw = 40 kDa) and PVA, and the mass ratio of PVP to PVA is 5:1.

[0052] Example 5

[0053] A laser cutting protective fluid comprising 5 wt% of a film former, 15 wt% of butanetetrol, 0.01 wt% of 1H-benzo[d]imidazole-2-sulfonic acid, 60 wt% of propylene glycol methyl ether, 300 ppm of dodecyl ethoxy sulfobetaine, and a balance of ultrapure water;

[0054] The film forming agent is PVP (Mw = 360 kDa) and PVA, and the mass ratio of PVP and PVA is 5:1.

[0055] Example 6

[0056] A laser cutting protective liquid, comprising 10 wt% of a film forming agent, 5 wt% of ethylene glycol, 0.03 wt% of 1H-benzo[d]imidazole-2-sulfonic acid, 60 wt% of propylene glycol methyl ether, 500 ppm of cocamidopropyl betaine, and the balance of ultrapure water;

[0057] The film forming agent is PVP (Mw = 360 kDa) and PVA, and the mass ratio of PVP and PVA is 5:1.

[0058] Example 7

[0059] A laser cutting protective liquid, comprising 5 wt% of a film forming agent, 10 wt% of glycerol, 0.05 wt% of 1H-benzo[d]imidazole-2-sulfonic acid, 80 wt% of propylene glycol methyl ether, 100 ppm of dodecyl ethoxy sulfobetaine, and the balance of ultrapure water;

[0060] The film forming agent is PVP (Mw = 40 kDa) and PVA, and the mass ratio of PVP and PVA is 5:1.

[0061] Comparative Example 1

[0062] A laser cutting protective liquid, which is basically the same as Example 1, except that the content of the film forming agent is 20 wt%.

[0063] Comparative Example 2

[0064] A laser cutting protective liquid, which is basically the same as Example 1, except that the content of the film forming agent is 3 wt%.

[0065] Comparative Example 3

[0066] A laser cutting protective liquid, which is basically the same as Example 1, except that the content of glycerol is 20 wt%.

[0067] Comparative Example 4

[0068] A laser cutting protective liquid, which is basically the same as Example 1, except that the content of glycerol is 3 wt%.

[0069] Comparative Example 5

[0070] A laser cutting protective liquid, which is basically the same as Example 1, except that it does not contain glycerol.

[0071] Comparative Example 6

[0072] A laser cutting protection fluid substantially identical to Example 1, except that the content of 1H-benzo[d]imidazole-2-sulfonic acid is 0.005 wt%.

[0073] Comparative Example 7

[0074] A laser cutting protection fluid substantially identical to Example 1, except that it does not contain 1H-benzo[d]imidazole-2-sulfonic acid.

[0075] Comparative Example 8

[0076] A laser cutting protection fluid substantially identical to Example 1, except that the content of dodecyl ethoxy sulfobetaine is 1000 ppm.

[0077] Comparative Example 9

[0078] A laser cutting protection fluid substantially identical to Example 1, except that the content of dodecyl ethoxy sulfobetaine is 50 ppm.

[0079] Comparative Example 10

[0080] A laser cutting protection fluid substantially identical to Example 1, except that it does not contain dodecyl ethoxy sulfobetaine.

[0081] Comparative Example 11

[0082] A laser cutting protection fluid substantially identical to Example 1, except that 1H-benzo[d]imidazole-2-sulfonic acid is replaced by benzenesulfonic acid.

[0083] Comparative Example 12

[0084] A laser cutting protection fluid substantially identical to Example 1, except that 1H-benzo[d]imidazole-2-sulfonic acid is replaced by benzimidazole.

[0085] Comparative Example 13

[0086] A laser cutting protection fluid substantially identical to Example 1, except that the film-forming agent is only PVP (Mw=40kDa).

[0087] Comparative Example 14

[0088] A laser cutting protection fluid substantially identical to Example 1, except that the film-forming agent is only PVP (Mw=40kDa), and it does not contain dodecyl ethoxy sulfobetaine.

[0089] Comparative Example 15

[0090] A laser cutting protective fluid, which is basically the same as that in Example 1, except that it does not contain glycerol and 1H-benzo[d]imidazole-2-sulfonic acid.

[0091] Comparative Example 16

[0092] A laser cutting protective fluid, which is basically the same as that in Example 1, except that the Mw of PVP is 10 kDa.

[0093] Comparative Example 17

[0094] A laser cutting protective fluid, which is basically the same as that in Example 1, except that the Mw of PVP is 500 kDa.

[0095] Comparative Example 18

[0096] A laser cutting protective liquid is basically the same as that in Example 1, except that dodecyl ethoxysulfonate is replaced with sodium dodecylbenzenesulfonate.

[0097] Test Example 1

[0098] The protective performance of the laser cutting protective fluids of Examples 1-7 and Comparative Examples 1-18 was tested, including their spin coating properties, cutting properties, and cleaning properties. The test methods are as follows:

[0099] (1) Spin coating test

[0100] One-step spin coating method: Take 40 mL of laser cutting protective liquid and drop it onto the surface of an 8-inch wafer. Use a spin coating device to spin coat at a speed of 1000 rpm for 120 s to ensure that the protective liquid is evenly spread to form a protective film.

[0101] (2) Cutting performance test

[0102] Pulsed laser was used for cutting, with the laser parameters set as follows: wavelength 355 nm, frequency 50 kHz, scribing speed 150 mm / s, cutting width 40 μm, and power 3.0 W. The wafer processing was completed according to the standard cutting procedure.

[0103] (3) Cleanability test

[0104] After cutting, the workpiece is cleaned with ultrapure water at a pressure of about 0.5 MPa.

[0105] The standards for evaluating the spin coating, cutting properties, and cleaning properties of various laser cutting protective fluids are as follows:

[0106] Excellent results are indicated by “□”, good results by “△”, and poor results by “×”.

[0107] Spinability evaluation: refers to the spin coating uniformity of the protective film, and requires that the wafer surface has no leakage points. A film thickness meter is used to measure the film thickness at 5 test points on the wafer: a maximum film thickness difference of ≤0.5 μm is excellent, 0.5 μm < maximum film thickness difference ≤1 μm is good, and a maximum film thickness difference >1 μm is poor;

[0108] Cutting evaluation: refers to that the workpiece has no edge collapse, no cracks and no PI layer burning after cutting. The state of the cut is observed by a metallographic microscope, and the yield is determined: a yield of ≥98% is excellent, 95%≤yield <98% is good, and a yield <95% is poor;

[0109] Cleaning evaluation: refers to that the workpiece has no sintering and no residue (including protective film residue and cutting generated particle and debris residue) after cleaning. The workpiece is dried by nitrogen after cleaning, and is observed by a metallographic microscope. If there is no residue, it is a qualified product, and the qualified yield is determined: a qualified yield of ≥98% is excellent, 95%≤qualified yield <98% is good, and a qualified yield <95% is poor.

[0110] The protective performance test results of the laser cutting protective liquid of Examples 1-7 and Comparative Examples 1-18 are shown in Table 1:

[0111] Table 1

[0112]

[0113]

[0114] From the comparison of the test results of Examples 1 and Comparative Examples 1, 2, it can be seen that the content of the film forming agent is negatively correlated with the spinability and the cleaning property. The higher the content of the film forming agent, the worse the spin coating uniformity, and the thicker the formed film layer, which increases the cleaning difficulty and easily leads to residue. If the content of the film forming agent is too low, the protective effect of the film layer cannot be guaranteed.

[0115] From the comparison of Example 1 and Comparative Examples 3, 4 and 5, it can be seen that when the content of the polyol is too high, the compactness of the film layer decreases, and the protective ability during cutting is weakened. If the content of the polyol is too low, the heat absorption effect is insufficient, and the water solubility of the film layer cannot be effectively improved, which easily leads to protective film residue after cleaning.

[0116] The comparison results of Example 1 and Comparative Examples 6 and 7 show that when the content of the ultraviolet absorber is less than 0.01 wt%, the absorption ability of the laser energy is greatly weakened, and it is difficult to inhibit the thermal damage during cutting.

[0117] The test data of Example 1 and Comparative Examples 8, 9 and 10 show that when the content of the betaine amphoteric surfactant is too high, a large amount of foam is generated, which destroys the spin coating uniformity. If the content is too low or not added at all, not only the spin coating effect is poor, but also the generated impurity particles during cutting cannot be effectively adsorbed, which still leads to residue after cleaning.

[0118] The comparative results of Example 1 and Comparative Examples 11, 12 show that the structural characteristics of the ultraviolet absorber are the key to its function, and the imidazole sulfonic acid compound can achieve excellent laser damage prevention effect, and the ultraviolet absorber containing only sulfonic acid group or imidazole group has significantly decreased protection performance.

[0119] The comparative analysis of Example 1 and Comparative Examples 13, 14 shows that there is a synergistic effect between the film-forming agent (PVP-PVA copolymer system) and the betaine type amphoteric surfactant - when only PVP is used as the film-forming agent, the spinability has been significantly deteriorated; if the betaine type amphoteric surfactant is also absent, the spinability is directly unqualified, while the combination of the two can significantly promote the uniform spreading of the film-forming agent on the wafer surface, and this synergistic effect cannot be achieved by simply combining PVP or PVA with the amphoteric surfactant.

[0120] The test results of Example 1 and Comparative Example 15 show that when the polyol and the ultraviolet absorber are both absent, the cutting performance is significantly deteriorated, indicating that there is a synergistic effect between the two in inhibiting laser heat damage and ensuring cutting quality, which together improves the cutting protection performance of the film layer.

[0121] The comparative results of Example 1 and Comparative Examples 16, 17 show that the molecular weight of PVP in the film-forming agent is crucial to the performance, and a too large (such as 500 kDa) or too small (such as 10 kDa) molecular weight will result in poor spin uniformity; and when the molecular weight is too large, the film layer cleaning difficulty is increased.

[0122] The test data of Example 1 and Comparative Example 18 show that after replacing the betaine type amphoteric surfactant with an anionic surfactant (sodium dodecyl benzene sulfonate), the spinability and cleanability are both significantly deteriorated, highlighting the unique advantages of the betaine type amphoteric surfactant in this system.

[0123] Figure 1 It is a physical picture of an 8-inch wafer after spin coating with the laser cutting protection liquid of Example 1, and the wafer surface presents a uniform and consistent luster, without any missed coating area, local unevenness or bubble defects. Figure 2 It is a metallographic microscope observation picture of a commercial wafer after spin coating with the laser cutting protection liquid of Example 1 and laser cutting, Figure 3 It is a metallographic microscope observation picture of a commercial wafer after spin coating with the laser cutting protection liquid of Example 2 and laser cutting. From Figure 2 and Figure 3 The characterization results of and show that the wafer cutting edge morphology is regular, without edge collapse and notch defects, the wafer edge does not appear micro-crack propagation phenomenon, and the surface PI protection layer does not produce carbonized focal spot damage.

[0124] Obviously, the above embodiments of the present application are only examples for clearly explaining the present application, and are not intended to limit the embodiments of the present application. It should be understood by those skilled in the art that other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and also impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A laser cutting protective fluid, characterized in that, The laser cutting protective fluid includes a film-forming agent, polyol, ultraviolet absorber, alcohol ether compound, betaine-type surfactant and ultrapure water; The film-forming agent includes polyvinylpyrrolidone and polyvinyl alcohol, wherein the weight-average molecular weight of polyvinylpyrrolidone is 40-360 kDa; The ultraviolet absorber is selected from one or more of 1H-benzimidazole-2-sulfonic acid, 1-benzyl-1H-benzimidazole-2-sulfonic acid, 1-propyl-1H-benzimidazole-2-sulfonic acid and 4,5-dihydro-1H-imidazol-2-sulfonic acid. The laser cutting protective solution contains 5-15 wt% film-forming agent; 5-15 wt% polyol; 0.01-0.05 wt% UV absorber; 40-80 wt% alcohol ether compounds; and 100-500 ppm betaine-type surfactant.

2. The laser cutting protective fluid according to claim 1, characterized in that, The mass ratio of polyvinylpyrrolidone to polyvinyl alcohol is (4-6):

1.

3. The laser cutting protective fluid according to claim 1, characterized in that, The degree of polymerization of the polyvinyl alcohol is 1000-2000; the degree of alcoholysis of the polyvinyl alcohol is 75-85; and the block distribution coefficient η of the polyvinyl alcohol is <1.

2.

4. The laser cutting protective fluid according to claim 1, characterized in that, The polyol is selected from one or more of ethylene glycol, propylene glycol, glycerol, and butanetetraol.

5. The laser cutting protective fluid according to claim 1, characterized in that, The alcohol ether compound is selected from one or more of propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and propylene glycol propyl ether.

6. The laser cutting protective fluid according to claim 1, characterized in that, The betaine-type surfactant is selected from one or more of cocamidopropyl betaine, dodecyl ethoxysulfonate betaine, dodecyl hydroxypropyl sulfonate betaine, and decyl hydroxypropyl sulfonate betaine.

7. The laser cutting protective fluid according to claim 1, characterized in that, The resistivity of the ultrapure water is greater than 18 MΩ·cm.

8. The laser cutting protective fluid according to claim 1, characterized in that, The ultrapure water content in the laser cutting protective fluid is 1-30 wt%.

9. A method for preparing the laser cutting protective fluid according to any one of claims 1-8, characterized in that, Includes the following steps: The laser cutting protective solution is obtained by mixing a film-forming agent, a polyol, a UV absorber, an alcohol ether compound, a betaine-type surfactant, and ultrapure water.

10. The method for preparing the laser cutting protective fluid according to claim 9, characterized in that, The mixing temperature is 20-40 ℃; after mixing, the mixture is stirred at a speed of 400-600 rpm for 1-3 h.

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