WO2021218662A1

WO2021218662A1 - Thermosetting resin composition which contains spherical silica powder and has no pit on polished surface after curing and preparation method therefor

Info

Publication number: WO2021218662A1
Application number: PCT/CN2021/087748
Authority: WO
Inventors: 李文; 黄江波; 方袁烽; 王珂
Original assignee: 浙江三时纪新材科技有限公司
Priority date: 2020-04-26
Filing date: 2021-04-16
Publication date: 2021-11-04

Abstract

A thermosetting resin composition which contains spherical silica powder and has no pit on a polished surface after curing, the thermosetting resin composition comprising spherical silica powder fillers not having internal pores and thermosetting resin, wherein spherical silica powder fillers having different particle sizes are closely filled and mixed in the thermosetting resin. The prevention invention also relates to a method for preparing the thermosetting resin composition, wherein a step of preparing the spherical silica powder filler not having internal pores comprises: P1: providing a spherical polysiloxane by a hydrolytic condensation reaction of R₁SiX₃, wherein the spherical polysiloxane comprises a T-unit with a content of 80% to 100%, R₁ is a hydrogen atom or an independently selectable organic group with carbon atoms 1 to 18, X is a hydrolyzable group, and the T-unit is R₁SiO₃-; and P2: calcining the spherical polysiloxanes in an oxidizing gas atmosphere conditions, the calcining temperature being between 850°C and 1200°C, the obtained spherical silica powder filler being suitable for 2.5D, 3D and other high-density chip packaging materials that require polishing in a packaging process.

Description

Thermosetting resin composition containing spherical silica powder without pits on polished surface after curing and preparation method thereof

Technical field

The invention relates to a circuit board, and more particularly to a thermosetting resin composition containing spherical silica powder without pits on the polished surface after curing and a preparation method thereof.

Background technique

With the continuous increase of semiconductor packaging density, more and more three-dimensional packaging forms such as 2.5D and 3D are used, such as TSMC's CoWoS packaging and InFO packaging. In these high-density packaging processes, the resin layer containing spherical silica filler needs to be polished, and then the circuit is formed. As the circuit layout space (line and space) is getting narrower and narrower, the requirements for packing are getting higher and higher. One of them is that there should be no holes inside the spherical silica, because if the porous silicon oxide inside the silicon oxide is partially polished and removed, pits will be formed on the polished surface. The pits will cause an open circuit on the circuit formed thereon, affecting the production of semiconductors. The spherical silica commonly used in the semiconductor industry is generally manufactured by the elemental silicon blasting method or flame melting method. The temperature of these processes is as high as 2300 degrees. It is inevitable that a part of spherical silica with internal holes will be produced, so it is not suitable High-density packaging with polishing process. Obviously, the filler composition provided by these known silicas is not suitable for packaging materials that need to be polished.

Summary of the invention

In order to solve the above-mentioned problem that the filler composition in the prior art cannot be applied to the packaging material that needs to be polished, the present invention aims to provide a thermosetting resin composition containing spherical silica powder without pits on the polished surface after curing.物 and its preparation method.

The invention provides a thermosetting resin composition containing spherical silica powder without pits on the polished surface after curing, wherein the thermosetting resin composition includes a spherical silica powder filler without internal pores and a thermosetting resin composition. The resin, in which spherical silica powder fillers of different particle diameters are tightly packed and graded in the thermosetting resin.

Preferably, the average particle size of the spherical silica powder filler is between 0.1 μm and 20 μm, and the thermosetting resin includes an epoxy resin and a curing agent.

The present invention also provides a method for preparing the above-mentioned thermosetting resin composition, which includes the steps: S1, respectively providing spherical silica powder filler and thermosetting resin without internal pores; S2, spherical silica powder with different particle diameters The filler is tightly packed and graded in the thermosetting resin to form a composite material, which is suitable for packaging materials that need to be polished.

Preferably, the form of the composite material obtained in step S2 is a liquid, a solid ingot or particle, and a semi-cured film.

Preferably, the composite material obtained in step S2 is sliced to obtain a cured sheet after curing. After the cured sheet is mirror polished, the cross-section of the spherical silica is observed with a field emission electron microscope, and 400 spheres with an average particle size of 1 micron to 50 microns are randomly observed. For silica, count the number of pits caused by internal holes with a diameter of 80 nanometers or more and less than 1/3 of the diameter of spherical silica, and the number of pits is 0.

Preferably, the preparation method of the spherical silica powder filler without internal pores comprises the steps: P1, the spherical polysiloxane is provided by the hydrolysis condensation reaction of _{R 1} SiX _{3, wherein the spherical polysiloxane includes} The content is 80%-100% of the T unit, R ₁ is a hydrogen atom or an independently selectable organic group of 1 to 18 carbon atoms, X is a water-decomposable group, and the T unit is R ₁ SiO ₃ -; P2, in Spherical polysiloxane is calcined in an oxidizing gas atmosphere, and the calcining temperature is between 850°C and 1200°C to obtain spherical silica powder filler without internal pores. The pore diameter of the internal pores is 80 nanometers. And 1/3 of the diameter of spherical silica.

Preferably, the spherical polysiloxane further contains Q units, D units, and/or M units, wherein Q unit = SiO ₄ -, D unit = R ₂ R ₃ SiO ₂ -, M unit = R ₄ R ₅ R ₆ SiO ₂ -, R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are each a hydrogen atom or an independently selectable hydrocarbon group of 1 to 18 carbon atoms. It should be understood that the spherical polysiloxane is dominated by T units, and the content of Q units, D units and/or M units should not be too high. Specifically, the T unit content of the present invention is between 80% and 100%, and the T unit content (%)=(((The number of silicon atoms per T unit content)/(T, Q, D, M unit content of silicon The sum of the number of atoms))×100)%. When the content of Q unit is too high, the adhesion of the spherical polysiloxane is serious; when the content of D unit and/or M unit is too high, the carbon content of the spherical polysiloxane is high, which is easy to crack or produce internal parts during calcination. hole. That is to say, the spherical polysiloxane with T unit as the main component of the present invention, especially polymethylsiloxane, is not easy to adhere in the synthesis stage, and the carbon content that needs to be burned during calcination is small, and it is not easy to break or break. Create internal pores to provide spherical silica powder filler without internal pores.

Preferably, the water-decomposable group X is an alkoxy group (e.g., methoxy group, ethoxy group, propoxy group, etc.) or a halogen atom (e.g. chlorine atom, etc.).

Preferably, the oxidizing gas contains oxygen to oxidize all the organic substances in the polysiloxane.

Preferably, the calcination temperature is between 950 degrees and 1100 degrees. It should be understood that too low a calcination temperature will result in insufficient silanol condensation, high water absorption will affect the dielectric properties and reliability, and too high a calcination temperature will cause serious adhesion of silica particles.

Preferably, the calcination time is between 6 hours and 12 hours.

Preferably, in step S2, a treatment agent is added to perform surface treatment on the spherical silica powder filler, the treatment agent includes a silane coupling agent and/or disilazane; the silane coupling agent is (R ₇ ) _a (R ₈ ) _b Si(M) _4-ab , R ₇ and R ₈ are independently selectable hydrocarbon groups with 1 to 18 carbon atoms, hydrogen atoms, or hydrocarbon groups with 1 to 18 carbon atoms replaced by functional groups, the The functional group is selected from at least one of the following organic functional groups: vinyl, allyl, styryl, epoxy, aliphatic amino, aromatic amino, methacryloxypropyl, acryloxypropyl Group, ureidopropyl group, chloropropyl group, mercaptopropyl group, polysulfide group, isocyanate propyl group; M is a hydrocarbyloxy group with 1 to 18 carbon atoms or a halogen atom, a=0, 1, 2 or 3, b = 0, 1, 2 or 3, a+b = 1, 2 or 3; the disilazane is (R ₉ R ₁₀ R ₁₁ )SiNHSi(R ₁₂ R ₁₃ R ₁₄ ), R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are independently selectable hydrocarbon groups with 1 to 18 carbon atoms or hydrogen atoms.

Preferably, in step S1, dry or wet sieving or inertial classification is used to remove 1 micrometer, 3 micrometers, 5 micrometers, 10 micrometers, 20 micrometers, 45 micrometers or more in the spherical silica powder filler. The coarse particles.

The spherical silica powder filler according to the present invention does not contain internal holes, and is suitable for 2.5D, 3D and other high-density chip packaging materials that need to be polished in the packaging process. It is mixed with thermosetting resin to obtain no pits on the polished surface after curing The thermosetting resin composition containing spherical silica powder. The internal pores mentioned here refer to the internal closed pores of the spherical silica powder. The detection method is to mix and cure thermosetting resins such as spherical silica and epoxy resin, and then slice them to obtain a cured sheet. After the cured sheet was mirror-polished, the cross-section of the spherical silica was observed with a field emission electron microscope, and the number of internal pores with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica was counted. In the present invention, substantially free of internal pores means that 400 spherical silicas with an average particle diameter of 1 micrometer to 50 micrometers are arbitrarily observed, and 0 spherical silicas have pores inside. In the conventional combustion explosion method and flame fusion method, 400 spherical silicas with an average particle diameter of 1 micron or more and 50 micrometers are arbitrarily observed, and there are generally 2-8 spherical silicas with pores inside. It should be understood that spherical silica below 1 micron generally does not contain internal pores due to its small particle size. In addition, the spherical silica used for chip packaging requires a clip segment to remove coarse particles, generally at least the coarse particles above 50 microns need to be removed. It should be further pointed out that the internal pores of silica mentioned here are pores that are enclosed in the inner part and have no passage with the outside. Therefore, the resin cannot enter the inner hole, and pits are generated when the cured product is polished. Holes, cracks, etc. that communicate with the outside can enter because of resin. Polishing after curing does not produce pits, which does not belong to the internal holes mentioned in the present invention.

Detailed ways

The preferred embodiments of the present invention are given below and described in detail.

The detection methods involved in the following embodiments include:

The average particle size is measured with HORIBA's LA-700 laser particle size distribution analyzer;

Detection of water content per unit specific surface area: Place the powder at a relative humidity of 65% and a temperature of 25 degrees for 24 hours and then use a Karl Fischer moisture meter to measure the water content at a temperature of 200 degrees. The water content per unit specific surface area = Karl Fischer The moisture meter measures the weight percentage of moisture (%)/specific surface area of the powder (m ² /g) at a temperature of 200 degrees;

The method for detecting the pits generated by the internal holes is to mix and cure the spherical silica and thermosetting resins such as epoxy resin and then slice them to obtain a cured sheet. After the cured sheet was mirror-polished, the cross-section of the spherical silica was observed with a field emission electron microscope, and the number of pits produced by internal holes with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica was counted. Arbitrarily observe the number of 400 spherical silicas with an average particle diameter of 1 micron or more and 50 microns or less/the amount of spherical silica having pits in 400 internal pores.

In this article, "degrees" refers to "degrees Celsius", that is, degrees Celsius.

In this context, the average particle size refers to the volume average diameter of the particles.

example 1

Take a certain weight of deionized water at room temperature and put it into a reactor with a stirrer, turn on the stirring, add 80 weight of methyltrimethoxysilane and a small amount of acetic acid to adjust the pH to about 5. After the methyltrimethoxysilane was dissolved, 25 parts by weight of 5% ammonia water was added and stirred for 10 seconds, and then the stirring was stopped. After standing for 1 hour, it is filtered and dried to obtain spherical polysiloxane. Put the polysiloxane powder into a muffle furnace and pass dry air into it for calcination. The final calcination temperature is 850 degrees, 1000 degrees or 1100 degrees, and the calcination time is 12 hours. The analysis results of the samples are listed in Table 1 below.

Table 1

Example 2

Take 1100 parts by weight of deionized water at room temperature and put it into a reactor with a stirrer, turn on the stirring, add 80 parts by weight of propyltrimethoxysilane and a small amount of acetic acid to adjust the pH to about 5. After the propyltrimethoxysilane was dissolved, 25 parts by weight of 5% ammonia water was added and stirred for 10 seconds, and then the stirring was stopped. After standing for 1 hour, it is filtered and dried to obtain spherical polysiloxane. Put the polysiloxane powder into a muffle furnace and pass dry air into it for calcination. The final calcination temperature is 950 degrees and the calcination time is 6 hours. The analysis results of the samples are listed in Table 2 below.

Table 2

Example 3

Take 2500 parts by weight of 40°C deionized water into a reactor with a stirrer, turn on the stirring, add 80 parts by weight of methyltrimethoxysilane and a small amount of acetic acid to adjust the pH to about 5. After the methyltrimethoxysilane was dissolved, 60 parts by weight of 5% ammonia water was added and stirred for 10 seconds, and then the stirring was stopped. After standing for 1 hour, it was filtered and dried to obtain spherical polysiloxane. Put the polysiloxane powder into a muffle furnace and pass dry air into it for calcination. The final calcination temperature is 1000 degrees and the calcination time is 12 hours. The analysis results of the samples are listed in Table 3 below.

table 3

Example 4

Take 1500 parts by weight of deionized water at room temperature, put it into a reactor with a stirrer, turn on the stirring, add 75 parts by weight of methyltrimethoxysilane and 25 parts by weight of tetraethoxysilane and stir for 1 hour. The T unit content is 82.1%. After the methyltrimethoxysilane and the tetraethoxysilane are dissolved, 25 parts by weight of 5% ammonia water is added and stirred for 10 seconds, and then the stirring is stopped to obtain a spherical polysiloxane. After drying, a spherical powder is obtained. Put the powder into a muffle furnace and slowly raise the temperature, discharge the organic matter in an oxygen-containing atmosphere and raise the temperature to 1000 degrees, and calcinate for 12 hours to obtain spherical hollow silica powder. The analysis results of the samples are listed in Table 4 below.

Table 4

Example 5

Take 600 parts by weight of deionized water at room temperature, put it into a reactor with a stirrer, turn on the stirring, add 78 parts by weight of methyltrimethoxysilane and 2 parts by weight of dimethyldimethoxysilane and stir. 1 hour. The T unit content is 97.2%. After the methyltrimethoxysilane and the dimethyldimethoxysilane were dissolved, 5 parts by weight of 5% ammonia water was added and stirred for 10 seconds, and then the stirring was stopped to obtain a spherical polysiloxane. After drying, a spherical powder is obtained. Put the powder into a muffle furnace and slowly raise the temperature to discharge the organic matter in an oxygen-containing atmosphere and raise the temperature to 950 degrees, calcining for 12 hours to obtain spherical hollow silica powder. The analysis results of the samples are listed in Table 5 below.

table 5

Example 6

Take a certain weight of deionized water at room temperature, put it into a reactor with a stirrer, turn on the stirring, add 78 weight parts of methyltrimethoxysilane and 2 weight parts of propyltrimethoxysilane and stir for 1 hour . After the methyltrimethoxysilane and the propyltrimethoxysilane were dissolved, 25 parts by weight of 5% ammonia water was added and stirred for 10 seconds, and then the stirring was stopped to obtain a spherical polysiloxane. After drying, a spherical powder is obtained. Put the powder into a muffle furnace and slowly raise the temperature, discharge the organic matter in an oxygen-containing atmosphere and raise the temperature to 950 degrees, and calcinate for 12 hours to obtain spherical hollow silica powder. The analysis results of the samples are listed in Table 6 below.

Table 6

Example 7

Example 8 (average particle size: 18 microns) 62 parts by weight, Example 4 (average particle size: 4.5 microns) 24 parts by weight, Example 2 (average particle size: 1.2 microns), 9 parts by weight, Example 7 (average particle size) (0.6 microns) 5 parts by weight are mixed and passed through a vibrating sieve with an opening of 25 microns to obtain powder A. 100 parts by weight of bisphenol A epoxy resin with epoxy equivalent of 180g/eg, 100 parts by weight of methyltetrahydrophthalic anhydride (curing agent) with anhydride equivalent of 160g/eg, amine adduct potential curing accelerator 6 parts by weight, 1 part by weight of 3-(2,3-glycidoxy)propyltrimethoxysilane, and 1400 parts by weight of powder A, stirred and mixed for 120 minutes and degassed under reduced pressure to obtain a liquid resin composition. The liquid resin composition was compressed and molded at 126 degrees for 10 minutes and cured, and then heated and cured at 150 degrees for 1 hour to obtain a sample piece. After the specimen was mirror-polished, the cross-section of the spherical silica was observed with a field emission electron microscope, and the number of pits produced by internal holes with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica was counted. Arbitrarily observe the number of 400 spherical silicas with an average particle diameter of 1 micron or more and 50 microns or less/the amount of spherical silica having pits in 400 internal pores.

In this example, the number of spherical silica pits is 0/400.

Example 8

Example 7 (with an average particle size of 0.6 microns) was passed through a vibrating sieve with an opening of 45 microns to obtain powder B. 100 parts by weight of bisphenol A epoxy resin with epoxy equivalent of 180g/eg, 100 parts by weight of methyltetrahydrophthalic anhydride (curing agent) with anhydride equivalent of 160g/eg, amine adduct potential curing accelerator 6 parts by weight, 1 part by weight of 3-(2,3-glycidoxy)propyltrimethoxysilane, and part by weight of powder B300, stirred and mixed for 120 minutes and degassed under reduced pressure to obtain a liquid resin composition. The liquid resin composition was compressed and molded at 126 degrees for 10 minutes and cured, and then heated and cured at 150 degrees for 1 hour to obtain a sample piece. After the specimen was mirror-polished, the cross-section of the spherical silica was observed with a field emission electron microscope, and the number of pits produced by internal holes with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica was counted. Arbitrarily observe the number of 400 spherical silicas with an average particle diameter of 1 micron or more and 50 microns or less/the amount of spherical silica having pits in 400 internal pores.

In this example, the number of spherical silica pits is 0/400.

Example 9

Example 8 (average particle size: 18 microns) was passed through a vibrating sieve with an opening of 45 microns to obtain powder C. 100 parts by weight of bisphenol A epoxy resin with epoxy equivalent of 180g/eg, 100 parts by weight of methyltetrahydrophthalic anhydride (curing agent) with anhydride equivalent of 160g/eg, amine adduct potential curing accelerator 6 parts by weight, 1 part by weight of 3-(2,3-glycidoxy)propyltrimethoxysilane, and part by weight of powder C300, stirred and mixed for 120 minutes and degassed under reduced pressure to obtain a liquid resin composition. The liquid resin composition was compressed and molded at 126 degrees for 10 minutes and cured, and then heated and cured at 150 degrees for 1 hour to obtain a sample piece. After the specimen was mirror-polished, the cross-section of the spherical silica was observed with a field emission electron microscope, and the number of pits produced by internal holes with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica was counted. Arbitrarily observe the number of 400 spherical silicas with an average particle diameter of 1 micron or more and 50 microns or less/the amount of spherical silica having pits in 400 internal pores.

In this example, the number of spherical silica pits is 0/400.

Comparative example 1

The commercially available flame melting method spherical silica (average particle size 16 microns) 62 parts by weight, the commercially available flame melting method spherical silica (average particle diameter 5 microns) 24 parts by weight, and the commercially available elemental silicon in oxygen combustion explosion method spherical two parts 9 parts by weight of silica (average particle size 1.5 microns) and 5 parts by weight of commercially available elemental silicon inflammable spherical silica (average particle size 0.6 microns) in oxygen are mixed and passed through a vibrating sieve with an opening of 25 microns to obtain powder D. 100 parts by weight of bisphenol A epoxy resin with epoxy equivalent of 180g/eg, 100 parts by weight of methyltetrahydrophthalic anhydride (curing agent) with anhydride equivalent of 160g/eg, amine adduct potential curing accelerator 6 parts by weight, 1 part by weight of 3-(2,3-glycidoxy)propyltrimethoxysilane, part by weight of powder D1400, stirred and mixed for 120 minutes and degassed under reduced pressure to obtain a liquid resin composition. The liquid resin composition was compressed and molded at 126 degrees for 10 minutes and cured, and then heated and cured at 150 degrees for 1 hour to obtain a sample piece. After the specimen was mirror-polished, the cross-section of the spherical silica was observed with a field emission electron microscope, and the number of pits produced by internal holes with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica was counted. Arbitrarily observe the number of 400 spherical silicas with an average particle diameter of 1 micron or more and 50 microns or less/the amount of spherical silica having pits in 400 internal pores. The number of spherical silica pits in Comparative Example 1 was 8/400.

Comparative example 2

Spherical silica (average particle size 0.6 micron) in the commercially available elemental silicon in oxygen gas was passed through a vibrating sieve with an opening of 45 micrometers to obtain powder E. 100 parts by weight of bisphenol A epoxy resin with epoxy equivalent of 180g/eg, 100 parts by weight of methyltetrahydrophthalic anhydride (curing agent) with anhydride equivalent of 160g/eg, amine adduct potential curing accelerator 6 parts by weight, 1 part by weight of 3-(2,3-glycidoxy)propyltrimethoxysilane, part by weight of powder E300, stirred and mixed for 120 minutes and degassed under reduced pressure to obtain a liquid resin composition. The liquid resin composition was compressed and molded at 126 degrees for 10 minutes and cured, and then heated and cured at 150 degrees for 1 hour to obtain a sample piece. After the specimen was mirror-polished, the cross-section of the spherical silica was observed with a field emission electron microscope, and the number of pits produced by internal holes with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica was counted. Arbitrarily observe the number of 400 spherical silicas with an average particle diameter of 1 micron or more and 50 micrometers/the amount of spherical silica having pits in 400 internal pores. The number of spherical silica pits in Comparative Example 2 was 28/400.

Comparative example 3

The commercially available flame-melting spherical silica (average particle size of 16 microns) was passed through a vibrating sieve with an opening of 45 microns to obtain powder F. 100 parts by weight of bisphenol A epoxy resin with epoxy equivalent of 180g/eg, 100 parts by weight of methyltetrahydrophthalic anhydride (curing agent) with anhydride equivalent of 160g/eg, amine adduct potential curing accelerator 6 parts by weight, 1 part by weight of 3-(2,3-glycidoxy)propyltrimethoxysilane, and part by weight of powder F300, stirred and mixed for 120 minutes and degassed under reduced pressure to obtain a liquid resin composition. The liquid resin composition was compressed and molded at 126 degrees for 10 minutes and cured, and then heated and cured at 150 degrees for 1 hour to obtain a sample piece. After the specimen was mirror-polished, the cross-section of the spherical silica was observed with a field emission electron microscope, and the number of pits produced by internal holes with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica was counted. Arbitrarily observe the number of 400 spherical silicas with an average particle diameter of 1 micron or more and 50 microns or less/the amount of spherical silica having pits in 400 internal pores. The number of spherical silica pits in Comparative Example 1 was 6/400.

It should be understood that the samples of the examples obtained in the foregoing Examples 1 to 9 can be surface-treated. Specifically, vinyl silane coupling agent, epoxy silane coupling, disilazane, etc. can be treated as needed. More than one type of treatment can be carried out as needed.

It should be understood that the preparation method includes the use of dry or wet sieving or inertial classification to remove coarse particles above 1, 3, 5, 10, and 20 microns in the filler.

The foregoing descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Various changes can be made to the foregoing embodiments of the present invention. That is to say, all simple and equivalent changes and modifications made in accordance with the claims of the present invention and the contents of the specification fall into the protection scope of the patent of the present invention. What is not described in detail in the present invention is conventional technical content.

Claims

A thermosetting resin composition containing spherical silica powder without pits on the polished surface after curing, characterized in that the thermosetting resin composition comprises a spherical silica powder filler without internal pores and a thermosetting resin , Among them, spherical silica powder fillers with different particle diameters are tightly packed and graded in thermosetting resin.
The thermosetting resin composition according to claim 1, wherein the average particle size of the spherical silica powder filler is between 0.1 μm and 20 μm, and the thermosetting resin includes an epoxy resin and a curing agent.
The preparation method of the thermosetting resin composition according to any one of claims 1-2, wherein the preparation method comprises the steps:

S1, respectively provide spherical silica powder filler and thermosetting resin without internal pores;

S2, spherical silica powder fillers of different particle sizes are tightly packed and graded in thermosetting resin to form a composite material, which is suitable for packaging materials that need to be polished.
The preparation method according to claim 3, wherein the composite material obtained in step S2 is in the form of liquid, solid ingots or particles, and semi-cured film.
The preparation method according to claim 3, characterized in that the composite material obtained in step S2 is sliced to obtain a cured sheet after curing, and the cured sheet is mirror-polished to observe the cross-section of the spherical silica with a field emission electron microscope, and the average particle size is arbitrarily observed. For 400 spherical silica with a diameter of 1 micron or more and 50 micrometers or less, count the number of pits caused by internal pores with a diameter of 80 nanometers or more and less than 1/3 of the diameter of the spherical silica, and the number of pits is 0.
The preparation method according to claim 3, wherein the preparation method of the spherical silica powder filler without internal pores comprises the following steps:

P1, the spherical polysiloxane is provided by the hydrolysis condensation reaction of R 1 SiX 3 , wherein the spherical polysiloxane includes a T unit content of 80%-100%, and R 1 is a hydrogen atom or can be independently selected An organic group having 1 to 18 carbon atoms, X is a water-decomposable group, and the unit of T is R 1 SiO 3 -;

P2, calcining spherical polysiloxane under oxidizing gas atmosphere, the calcining temperature is between 850°C and 1200°C to obtain spherical silica powder filler without internal pores. The pore diameter of the internal pores is between Between 80 nanometers and 1/3 of the diameter of spherical silica.
The preparation method according to claim 6, wherein the spherical polysiloxane further contains Q units, D units, and/or M units, wherein Q unit = SiO 4 -, D unit = R 2 R 3 SiO 2 -, M unit = R 4 R 5 R 6 SiO 2 -, R 2 , R 3 , R 4 , R 5 , and R 6 are each a hydrogen atom or an independently selectable hydrocarbon group of 1 to 18 carbon atoms.
The preparation method according to claim 6, wherein the water-decomposable group X is an alkoxy group or a halogen atom.
The preparation method according to claim 3, characterized in that, in step S2, a treatment agent is added to perform surface treatment on the spherical silica powder filler, and the treatment agent includes a silane coupling agent and/or disilazane. Alkane; the silane coupling agent is (R 7 ) a (R 8 ) b Si(M) 4-ab , R 7 , R 8 are independently selectable hydrocarbon groups with 1 to 18 carbon atoms, hydrogen atoms, or functional groups The substituted hydrocarbon group with 1 to 18 carbon atoms, the functional group is selected from at least one of the following organic functional groups: vinyl, allyl, styryl, epoxy, aliphatic amino, aromatic amino, methyl Acryloyloxypropyl, acryloxypropyl, ureidopropyl, chloropropyl, mercaptopropyl, polysulfide group, isocyanate propyl group; M is a hydrocarbyloxy group with 1 to 18 carbon atoms or a halogen atom, a=0, 1, 2 or 3, b=0, 1, 2 or 3, a+b=1, 2 or 3; the disilazane is (R 9 R 10 R 11 )SiNHSi(R 12 R 13 R 14 ), R 9 , R 10 , R 11 , R 12 , R 13 and R 14 are independently selectable hydrocarbon groups with 1 to 18 carbon atoms or hydrogen atoms.
The preparation method according to claim 3, characterized in that, in step S1, dry or wet sieving or inertial classification is used to remove 1 micron, 3 micron, 5 micron in the spherical silica powder filler. Coarse particles larger than micrometers, 10 micrometers, 20 micrometers, and 45 micrometers.