Alkali-resistant spherical silica slurry for package substrate and preparation method therefor

Abstract

An alkali-resistant spherical silica slurry for a package substrate and a preparation method therefor. The preparation method comprises: first compounding submicron spherical silica and micron spherical silica, performing wet-process modification on compounded spherical silica A with a silane coupling agent, then carrying out secondary modification with a non-polar short-chain silane coupling agent, and finally dispersing the modified silica in an organic solvent and grading to obtain a spherical silica slurry. The spherical silica slurry has good stability, reasonable product particle size distribution, and uniform modifier coating; and when applied in a package substrate, the spherical silica slurry shows good alkali resistance, and has good flowability and low melt viscosity.

Description

Alkali-resistant spherical silica slurry for packaging substrate and preparation method thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 22, 2023, with application number CN202311782512.3 and invention name “Alkali-resistant spherical silica slurry for packaging substrates and preparation method thereof”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of inorganic fillers and relates to an alkali-resistant spherical silica slurry for packaging substrates and a preparation method thereof. Background Art

[0003] The package substrate, also known as the IC substrate, is a key material used to connect the chip to the PCB motherboard in IC packaging. It has replaced traditional leadframes in mid- to high-end packaging applications. The main functions of the IC substrate include providing chip protection, support, and heat dissipation. Similar in structure and function to PCBs, IC substrates evolved from HDI boards. However, the technical requirements for IC substrates are far higher than those for both HDI and conventional PCBs. They feature high density, high precision, a high pin count, high performance, miniaturization, and thinness, and they also require higher technical parameters such as line width and line spacing.

[0004] Package substrates have high CTE requirements. Besides high fluidity, they also require strong bonding between the filler and the resin, good alkali resistance, and low surface roughness after Desmear treatment (to remove glue residue during drilling). Poor alkali resistance leads to high surface roughness after Desmear treatment, which can compromise long-term interlayer insulation reliability.

[0005] Chinese patent CN106700132BA discloses a silica slurry composition that uses nano-sized silica coated on the surface of silica powder and dispersed in an organic solvent. This product, used in laminates, exhibits good dispersibility and fluidity. However, the addition of nano-spherical silica does not improve its alkali resistance.

[0006] Chinese patent CN109021292A discloses a slurry composition. A plasma-modified silica surface is coated with a layer of a weakly polar or non-polar monomer, which is then dispersed in an organic solvent to prepare a silica slurry composition. The composition exhibits good dispersibility, fluidity, and dielectric properties. Furthermore, due to the uniform coating of the modifier, it exhibits good sedimentation stability. However, the plasma modification employed in this method is difficult to commercialize.

[0007] Summary of the Invention

[0008] The purpose of the present application is to provide an alkali-resistant spherical silica slurry for a packaging substrate with good stability and a preparation method thereof.

[0009] The technical solutions for achieving the purpose of this application are as follows:

[0010] The preparation method of alkali-resistant spherical silica slurry for packaging substrates comprises the following specific steps:

[0011] (1) Raw material compounding:

[0012] Set D50=0.3-0.8μm, D100≤5.0μm, SSA=4.0-12.0m 2 / g of submicron spherical silica and D50 = 1.0-3.0 μm, D100 ≤ 5.0 μm, SSA = 0.5-4.0 μm 2 / g of micron spherical silica is mixed in a mass ratio of 1:3-3:1 to obtain D50 = 0.4-2.0μm, D100 ≤ 5.0μm, SSA = 1.5-9.0m 2 / g of spherical silica A;

[0013] (2) Wet modification:

[0014] The spherical silica A and water are uniformly mixed and pre-dispersed in a mass ratio of 3:7-6:4 to obtain a submicron slurry, and then a modifier is added to perform wet grinding for preliminary modification. The preliminarily modified slurry is then dried at 120-300° C. to modify the slurry until the moisture content is ≤0.3%, and then kept warm at 60-120° C. Finally, the kept material is depolymerized to a particle size consistent with that of the spherical silica A to obtain wet-modified spherical silica B, wherein the modifier is selected from an epoxy silane coupling agent, an aniline silane coupling agent, an isocyanate silane coupling agent, or a urea silane coupling agent;

[0015] (3) Secondary modification:

[0016] Using a non-polar short-chain silane coupling agent to perform secondary modification on the wet-modified spherical silica B to obtain secondary-modified spherical silica C, wherein the non-polar short-chain silane coupling agent is a short-chain alkylsilane coupling agent or silazane;

[0017] (4) Slurrying:

[0018] The secondary modified spherical silica C is pre-dispersed in an organic solvent under stirring, then dispersed in a disperser, and then classified to remove large particles to obtain an alkali-resistant spherical silica slurry for packaging substrates. The organic solvent is acetone, butanone, methyl isobutyl ketone (MIBK) or cyclohexanone.

[0019] Preferably, in step (2), the pre-dispersion is carried out using a sand mill, and the pre-dispersion temperature is 50-90°C.

[0020] Preferably, in step (2), the insulation time is 20-60 minutes.

[0021] Preferably, in step (2), the depolymerization is carried out using a jet mill, and the depolymerization pressure is ≥1.0 MPa.

[0022] Preferably, in step (2), the mass ratio of the modifier to the spherical silica A is 0.1-2.0:100.

[0023] Preferably, in step (2), the epoxy silane coupling agent is 3-glycidylpropyltrimethoxysilane, the anilino silane coupling agent is N-phenyl-3-aminopropyltrimethoxysilane, the isocyanate silane coupling agent is 3-isocyanatepropyltriethoxysilane, and the urea silane coupling agent is 3-ureapropyltriethoxysilane.

[0024] Preferably, in step (3), the short-chain alkylsilane coupling agent is selected from methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, dimethyldimethoxysilane or trimethylmethoxysilane, and the silazane is hexamethyldisilazane or tetramethyldisilazane;

[0025] Preferably, in step (3), the mass ratio of the non-polar short-chain silane coupling agent to the spherical silica B is 0.1-1.0:100.

[0026] Preferably, in step (3), the equipment used for the secondary modification is a high-speed stirrer, the temperature of the secondary modification is 80-150° C., and the time of the secondary modification is 10-40 min.

[0027] Preferably, in step (4), the mass ratio of the spherical silica C to the organic solvent is 25:75-50:50.

[0028] Preferably, in step (4), the disperser is a high-pressure homogenizer, and the dispersion pressure is 10,000 psi-20,000 psi; the equipment used for grading is a wet vibrating screen, and the mesh size of the wet vibrating screen is ≤10 μm; and the equipment used for drying and modification is a flash dryer.

[0029] The alkali-resistant spherical silica slurry for packaging substrates is prepared by the preparation method described in the above technical solution.

[0030] Compared with the prior art, this application has the following advantages:

[0031] (1) This application uses submicron spherical silica with a small specific surface area and narrow distribution. The micron spherical silica has a small specific surface area and has little interfacial contact with the resin during use. At the same time, the combination of large and small balls can improve alkali resistance, and the surface roughness is low after Desmear treatment.

[0032] (2) This application uses a polar silane coupling agent for wet modification, resulting in uniform coating. Short-chain silane is then used for secondary modification. The presence of polar groups improves the compatibility of the filler (silicon dioxide) with the resin, while the presence of non-polar groups improves the dispersibility of the filler (silicon dioxide). Consequently, the filler exhibits good alkali resistance during use, and the surface roughness is low after Desmear treatment. The synergistic effect of the silane coupling agent and the non-polar short-chain silane is utilized to further improve the stability and fluidity of the product.

[0033] (3) The spherical silica slurry product prepared in this application has good stability and is used in packaging substrates. It has good alkali resistance and low surface roughness after Desmear treatment. At the same time, the production process is easy to control, the product has good stability, and is suitable for mass production. DETAILED DESCRIPTION

[0034] The present application will be further described below in conjunction with specific embodiments.

[0035] The test methods for silicon powder D50, D100, pH, TGA weight loss, viscosity, and flow time in the following examples and comparative examples are as follows:

[0036] (1) D50 and D100 tests: tested using the American Beckman Coulter LS13320 laser particle size analyzer;

[0037] (2) Sedimentation stability: Pour the slurry into a 100 ml stoppered test tube to the 100 ml mark, seal it, and store it at room temperature. After one month, observe the slurry for stratification, record the height of the separated clear liquid, and invert it to observe whether there is sedimentation at the bottom. The less stratification and bottom sedimentation, the better the product stability.

[0038] (3) Melt Viscosity Test: The product is used in the carrier formulation. The rheological curve of the prepreg resin powder in the range of 80 to 190°C is tested to determine the minimum melt viscosity (η). The lower the minimum melt viscosity, the better the flowability.

[0039] Example 1

[0040] (1) Raw material compounding

[0041] Set D50=0.50μm, D100=2.6μm, SSA=6.6m 2 / g of submicron spherical silica with D50 = 1.5μm, D100 = 2.2μm, SSA = 2.6m 2 / g of micron spherical silica were mixed in a mass ratio of 1:1 to obtain D50 = 0.93 μm, D100 = 2.6 μm, SSA = 4.6 m 2 / g of spherical silica A;

[0042] (2) Wet modification

[0043] Spherical silica A and deionized water were mixed in a mass ratio of 1:1 and then sent to a sand mill for pre-dispersion. The pre-dispersion temperature was controlled at 80°C. After uniform dispersion, a submicron slurry was obtained. Then, 0.6% of the mass of spherical silica A by weight of N-phenyl-3-aminopropyltrimethoxysilane KBM-573 (Shin-Etsu Chemical) was added and wet-ground for preliminary modification. The preliminarily modified slurry was then sent to a flash dryer for dry modification at an inlet air temperature of 250°C. After drying to a moisture content of ≤0.3%, it was sent to a collector for insulation at a temperature of 110°C for 30 minutes. The insulated material was then depolymerized in a jet mill at a depolymerization pressure of 1.0 MPa to obtain wet-modified spherical silica B.

[0044] (3) Secondary modification

[0045] Spherical silica B was added to a high-speed blender, along with methyltrimethoxysilane KBM-13 (Shin-Etsu Chemical), and modified at 100°C for 20 minutes to obtain secondary modified spherical silica C. The mass ratio of methyltrimethoxysilane KBM-13 to spherical silica B was 0.3:100.

[0046] (4) Slurry

[0047] Spherical silica C and organic solvent acetone were added to a stirring barrel in a mass ratio of 7:3 for preliminary dispersion, and then dispersed by a homogenizer under a pressure of 10,000 psi. Then, a sieve with a pore size of 5 μm was used to sieve out large particles to obtain an alkali-resistant spherical silica slurry for packaging substrates.

[0048] Example 2

[0049] (1) Raw material compounding

[0050] Set D50=0.78μm, D100=3.5μm, SSA=5.2m 2 / g of submicron spherical silica with D50 = 2.0 μm, D100 = 3.5 μm, SSA = 1.8 μm 2 / g of micron spherical silica were mixed in a mass ratio of 1:2 to obtain D50 = 1.2μm, D100 = 3.5μm, SSA = 4.8m 2 / g of spherical silica A;

[0051] (2) Wet modification

[0052] Spherical silica A and deionized water were mixed in a mass ratio of 6:4, and then sent to a sand mill for pre-dispersion. The pre-dispersion temperature was controlled at 60°C. After uniform dispersion, a submicron slurry was obtained. Then, 0.8% of the mass of spherical silica A was added with 3-glycidylpropyltrimethoxysilane KBM-403 (Shin-Etsu Chemical), and wet-grinded for preliminary modification. The preliminarily modified slurry was then sent to a flash dryer for drying and modification at an inlet air temperature of 150°C. After drying to a moisture content of ≤0.3%, it was sent to a collector for insulation at a temperature of 100°C for 60 minutes. The insulated material was then depolymerized by a jet mill at a depolymerization pressure of 1.0 MPa to obtain wet-modified spherical silica B.

[0053] (3) Secondary modification

[0054] Spherical silica B was added to a high-speed mixer, and dimethyldimethoxysilane KBM-22 (Shin-Etsu Chemical) was added simultaneously, and modified at 100°C for 20 minutes to obtain secondary modified spherical silica C. The mass ratio of dimethyldimethoxysilane KBM-22 to spherical silica B was 0.3:100.

[0055] (4) Slurry

[0056] Spherical silica C and organic solvent butanone were added to a stirring barrel in a mass ratio of 7:3 for preliminary dispersion, and then dispersed by a homogenizer under a pressure of 10,000 psi. Then, a sieve with a pore size of 10 μm was used to sieve out large particles to obtain an alkali-resistant spherical silica slurry for packaging substrates.

[0057] Example 3

[0058] (1) Raw material compounding

[0059] Set D50=0.36μm, D100=0.87μm, SSA=11.6m 2 / g submicron spherical silica with D50=1.1μm, D100=2.0μm, SSA=3.2m 2 / g of micron spherical silica were mixed in a mass ratio of 1:2 to obtain D50 = 0.59 μm, D100 = 2.0 μm, SSA = 6.0 μm 2 / g of spherical silica A;

[0060] (2) Wet modification

[0061] Spherical silica A and deionized water were mixed in a mass ratio of 4:6, and then sent to a sand mill for pre-dispersion. The pre-dispersion temperature was controlled at 60°C. After uniform dispersion, a submicron slurry was obtained. Then, 2.0% of 3-ureapropyltriethoxysilane KBE-585 (Shin-Etsu Chemical) by mass of spherical silica A was added and wet-ground for preliminary modification. The preliminarily modified slurry was then sent to a flash dryer for drying and modification at an inlet air temperature of 220°C. After drying to a moisture content of ≤0.3%, it was sent to a collector for insulation at a temperature of 120°C for 30 minutes to complete the secondary modification. The insulated material was then depolymerized by a jet mill at a depolymerization pressure of 1.0 MPa to obtain wet-modified spherical silica B.

[0062] (3) Secondary modification

[0063] Spherical silica B was added to a high-speed blender, along with hexamethyldisilazane SZ-13 (Shin-Etsu Chemical), and modified at 110°C for 20 minutes to obtain secondary modified spherical silica C. The mass ratio of hexamethyldisilazane SZ-13 to spherical silica B was 0.8:100.

[0064] (4) Slurry

[0065] Spherical silica C and organic solvent butanone were added to a stirring barrel in a mass ratio of 7:3 for preliminary dispersion, and then dispersed by a homogenizer under a pressure of 10,000 psi. Then, a sieve with a pore size of 5 μm was used to sieve out large particles to obtain an alkali-resistant spherical silica slurry for packaging substrates.

[0066] Example 4

[0067] (1) Raw material compounding

[0068] Set D50=0.50μm, D100=2.6μm, SSA=6.6m 2 / g of submicron spherical silica with D50 = 1.5μm, D100 = 2.2μm, SSA = 2.6m 2 / g of micron spherical silica were mixed in a mass ratio of 1:1 to obtain D50 = 0.93 μm, D100 = 2.6 μm, SSA = 4.6 m 2 / g of spherical silica A;

[0069] (2) Wet modification

[0070] Spherical silica A and deionized water were mixed in a mass ratio of 3:7, and then sent to a sand mill for pre-dispersion. The pre-dispersion temperature was controlled at 70°C. After uniform dispersion, a submicron slurry was obtained. Then, 1.0% of 3-isocyanate propyltriethoxysilane KBE-9007N (Shin-Etsu Chemical) by mass of the spherical silica A was added and wet-grinded to complete the preliminary modification. The preliminarily modified slurry was then sent to a flash dryer for drying and modification at an inlet air temperature of 180°C. After drying to a moisture content of ≤0.3%, it was sent to a collector for insulation at a temperature of 100°C for 60 minutes. The insulated material was then depolymerized by a jet mill at a depolymerization pressure of 1.0 MPa to obtain wet-modified spherical silica B.

[0071] (3) Secondary modification

[0072] Spherical silica B was added to a high-speed blender, along with methyltrimethoxysilane KBM-13 (Shin-Etsu Chemical), and modified at 100°C for 20 minutes to obtain secondary modified spherical silica C. The mass ratio of methyltrimethoxysilane KBM-13 to spherical silica B was 0.5:100.

[0073] (4) Slurry

[0074] Spherical silica C and organic solvent methyl isobutyl ketone (MIBK) were added to a stirring barrel in a mass ratio of 7:3 for preliminary dispersion, and then dispersed through a homogenizer under a pressure of 10,000 psi. The mixture was then sieved using a sieve with a pore size of 5 μm to remove large particles, thereby obtaining an alkali-resistant spherical silica slurry for packaging substrates.

[0075] Comparative Example 1

[0076] This comparative example is substantially the same as Example 1, except that dry modification is adopted in step (2), specifically, spherical silica A is added to a high-speed mixer and stirred, and 0.6% KBM-573 (Shin-Etsu Chemical) aniline silane coupling agent is added at the same time, and the mixture is modified at 110° C. for 30 minutes to obtain spherical silica B.

[0077] Comparative Example 2

[0078] This comparative example is substantially the same as Example 1, except that micron-shaped spherical silica is not added in step (1).

[0079] Comparative Example 3

[0080] This comparative example is substantially the same as Example 1, except that the silane coupling agent in step (2) is vinyltrimethoxysilane KBM-1003.

[0081] Comparative Example 4

[0082] This comparative example is substantially the same as Example 1, except that step (3) is not performed.

[0083] Comparative Example 5

[0084] This comparative example is substantially the same as Example 1, except that the silane coupling agent in step (3) is decyltrimethoxysilane KBM-3103 (Shin-Etsu Chemical).

[0085] The stability of the silicon dioxide slurries prepared in the examples and comparative examples was tested, and the results are shown in Table 1.

[0086] Table 1 Sedimentation results of silicon dioxide slurries prepared in Examples and Comparative Examples

[0087] As can be seen from Table 1: After being placed for 1 month, the layer height of Examples 1-4 is less, and there is no sediment at the bottom after inversion, indicating that the stability of the slurry products of the examples is better. Compared with Example 1, the modification process in step (2) of Comparative Example 1 is different. Example 1 uses a wet modification, while Comparative Example 1 uses a dry modification. The layer height of Comparative Example 1 is higher and there is sediment at the bottom, indicating that wet modification is beneficial to improving sedimentation stability. Compared with Example 1, Comparative Example 2 does not add micron spherical silica to the raw materials, and the layer height of Comparative Example 2 is slightly less, and there is no sediment at the bottom. The stability of the slurry product is also better, indicating that the addition of micron spherical silica is not good for sedimentation stability, but the effect is not obvious. Compared with Example 1, the type of modifier in step (2) of Comparative Example 3 is different, and the layer height in Comparative Example 3 is close to that of Example 1, and there is no sediment at the bottom. The stability of the slurry product is still good, indicating that the type of modifier in step (2) has no obvious effect on the stability of the slurry product. Compared with Example 1, Comparative Example 4 does not contain step 3, and the slurry product has many layers and sediment at the bottom, indicating that step 3 can improve sedimentation stability. Compared with Example 1, Comparative Example 5 uses a different modifier, long-chain alkylsilane KBM-3103, and the slurry product of Comparative Example 5 has many layers and sediment at the bottom, indicating that the chain length of the alkylsilane in step (3) affects the stability of the product.

[0088] SC2050MT*, a leading international slurry product, along with slurries from the examples and comparative examples, were used in a BT resin encapsulation substrate formulation with a filler ratio of 65%. The melt viscosity and post-desmear weight loss of the products were tested. Lower desmear weight loss indicates less surface roughness after desmearing, indicating better alkali resistance. The melt viscosities and desmear weight loss of the products are shown in Table 2.

[0089] Table 2 Melt viscosity of the package substrates prepared in the examples and comparative examples and weight loss rate of the plates after desmear

[0090] As can be seen from Table 2: the minimum melt viscosity of the examples is close to that of SC2050MT*, and the weight loss rate after desmear is lower than that of SC2050MT*, indicating that the fluidity of the products of this application is close to that of foreign counterparts, and the alkali resistance is better than that of foreign counterparts. Compared with Example 1, the modification process in step (2) is different in Example 1. Example 1 uses a wet modification, while Comparative Example 1 uses a dry modification. The weight loss rate after desmear in Comparative Example 1 is large and the melt viscosity is large, indicating that the wet modification used in this application has good alkali resistance and low melt viscosity. Compared with Example 2, no micron spherical silica is added to the raw materials, while Comparative Example 2 has a large weight loss rate and a large melt viscosity after desmear, indicating that the addition of micron spherical silica can improve alkali resistance and melt viscosity. Compared with Example 1, the type of modifier in step (2) is different in Comparative Example 3, and the weight loss rate and melt viscosity after desmear in Comparative Example 3 are large, indicating that the type of modifier in step (2) affects the alkali resistance and melt viscosity of the slurry product. Compared with Example 1, Comparative Example 4 does not contain step (3), and the product of Comparative Example 4 has a large weight loss rate and a large melt viscosity after desmearing, indicating that step (3) can improve alkali resistance and melt viscosity. Compared with Example 1, Comparative Example 5 uses a different modifier. Comparative Example 5 uses a long-chain alkylsilane KBM-3103, and the slurry product of Comparative Example 5 has a slightly large weight loss rate and a large melt viscosity after desmearing, indicating that the chain length of the alkylsilane in step (3) affects the alkali resistance and melt viscosity of the product.

[0091] Although the above embodiment provides a detailed description of the present application, it is only a part of the embodiments of the present application rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present application.

Claims

1. A method for preparing an alkali-resistant spherical silica slurry for a packaging substrate, characterized in that: The specific steps are as follows: (1) Raw material compounding: Set D50=0.3-0.8μm, D100≤5.0μm, SSA=4.0-12.0m 2 / g of submicron spherical silica and D50 = 1.0-3.0μm, D100 ≤ 5.0μm, SSA = 0.5-4.0m 2 / g of micron spherical silica is mixed in a mass ratio of 1:3-3:1 to obtain D50 = 0.4-2.0 μm, D100 ≤ 5.0 μm, SSA = 1.5-9.0 m 2 / g of spherical silica A; (2) Wet modification: The spherical silicon dioxide A and water are uniformly mixed in a mass ratio of 3:7-6:4 for pre-dispersion to obtain a submicron slurry, and then a modifier is added to perform wet grinding for preliminary modification, and then the preliminarily modified slurry is dried and modified at 120-300° C., and after drying to a moisture content of ≤0.3%, the slurry is kept warm at 60-120° C., and finally the kept material is depolymerized to a particle size consistent with that of the spherical silicon dioxide A to obtain wet-modified spherical silicon dioxide B, wherein the modifier is selected from an epoxy silane coupling agent, an anilino silane coupling agent, an isocyanate silane coupling agent or a urea silane coupling agent; (3) Secondary modification: Using a non-polar short-chain silane coupling agent to perform secondary modification on the wet-modified spherical silica B to obtain secondary modified spherical silica C, wherein the non-polar short-chain silane coupling agent is a short-chain alkyl silane coupling agent or silazane; (4) Slurry: The secondary modified spherical silica C is pre-dispersed in an organic solvent under stirring, then dispersed in a disperser, and then classified to remove large particles to obtain an alkali-resistant spherical silica slurry for packaging substrates. The organic solvent is acetone, butanone, methyl isobutyl ketone or cyclohexanone.

2. The preparation method according to claim 1, characterized in that: In step (2), the pre-dispersion is carried out by a sand mill, the pre-dispersion temperature is 50-90° C., the insulation time is 20-60 min, and the depolymerization is carried out by a jet mill, the depolymerization pressure is ≥1.0 MPa.

3. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of the modifier to the spherical silica A is 0.1-2.0:

100.

4. The preparation method according to claim 1, characterized in that: In step (2), the epoxy silane coupling agent is 3-glycidylpropyltrimethoxysilane, the anilino silane coupling agent is N-phenyl-3-aminopropyltrimethoxysilane, the isocyanate silane coupling agent is 3-isocyanatepropyltriethoxysilane, and the urea silane coupling agent is 3-ureapropyltriethoxysilane.

5. The preparation method according to claim 1, characterized in that: In step (3), the short-chain alkyl silane coupling agent is selected from methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, dimethyldimethoxysilane or trimethylmethoxysilane, and the silazane is hexamethyldisilazane or tetramethyldisilazane.

6. The preparation method according to claim 1, characterized in that: In step (3), the mass ratio of the non-polar short-chain silane coupling agent to the spherical silica B is 0.1-1.0:

100.

7. The preparation method according to claim 1, characterized in that: In step (3), the equipment used for the secondary modification is a high-speed mixer, the temperature of the secondary modification is 80-150° C., and the time of the secondary modification is 10-40 min.

8. The preparation method according to claim 1, characterized in that: In step (4), the mass ratio of the spherical silica C to the organic solvent is 25:75-50:

50.

9. The preparation method according to claim 1, characterized in that: In step (4), the disperser is a high-pressure homogenizer, and the dispersion pressure is 10000psi-20000psi; the equipment used for classification is a wet vibrating screen, and the mesh size of the wet vibrating screen is ≤10μm; the equipment used for drying and modification is a flash dryer.

10. Alkali-resistant spherical silica slurry for packaging substrates obtained by the preparation method according to any one of claims 1 to 9.

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