Large particle size spherical silica, method for preparing same, and copper clad plate

Abstract

The present application relates to the technical field of silica preparation, in particular to large-particle-size spherical silica, a preparation method thereof and a copper-clad plate. The large-particle-size spherical silica has a ball breakage rate < 20%, Span1 < 2.5 and Span2 < 1.5. The large-particle-size spherical silica with no breakage on the surface greatly reduces interface loss, greatly improves the dielectric properties of the silica and reduces dielectric loss. Meanwhile, the spherical silica can be obtained by the processes of degassing, dispersion, calcination and superfine processing of polysiloxane microspheres. The processes also improve the problem of adhesion of the spheres caused by multiple sintering.

Description

Technical Field

[0001] This invention relates to the field of silicon dioxide preparation technology, and more specifically, to large-particle-size spherical silicon dioxide, its preparation method, and copper-clad laminates. Background Technology

[0002] With the development of 5G technology, significant changes have occurred in peak data rates, spectral efficiency, and latency, placing new demands on printed circuit board (PCB) and copper-clad laminate (CCL) materials. High-frequency, high-speed CCLs are categorized into RF / microwave CCLs (high-frequency CCLs) and high-speed digital CCLs (high-speed CCLs). To meet the demands of 5G technology, high-frequency, high-speed CCLs require low signal loss, lightweight design, and multifunctionality, thus placing higher demands on their fillers: low dielectric constant (Dk), low dielectric loss (Df), low coefficient of thermal expansion (CTE), and high thermal conductivity.

[0003] In existing technologies, polysiloxane microspheres are commonly calcined to remove organic matter, resulting in spherical silica that meets the above requirements. However, large-diameter spherical polysiloxane microspheres (2-20 micrometers in diameter) are difficult to clean due to their large size. Industry solutions for calcining large-diameter spherical silica generally fall into two categories: increasing the calcination temperature and increasing the calcination time through multiple calcinations, sometimes exceeding five times. While increasing the calcination temperature improves organic matter removal efficiency, high temperatures can cause silica to melt, leading to sintering and a loss of shape, resulting in serious problems like material burning. Similarly, extending the calcination time at a safe temperature improves efficiency, but prolonged calcination causes material agglomeration and adhesion between microspheres. Subsequent breakage can lead to surface breakage, increasing dielectric loss and reducing material performance.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide large-particle-size spherical silica, its preparation method, and copper-clad laminate.

[0006] This invention provides large-diameter spherical silica spheres with undamaged surfaces, significantly reducing interfacial losses and greatly improving the dielectric properties of silica while reducing dielectric loss. It also provides a method for preparing such spherical silica, which can be obtained through a process of debinding, dispersing, calcining, and ultrafine processing of polysiloxane microspheres. This process also improves the problem of sphere adhesion caused by multiple sintering processes.

[0007] This invention is implemented as follows:

[0008] In a first aspect, the present invention provides large-particle-size spherical silica, wherein the large-particle-size spherical silica meets the following requirements: sphere loss rate < 20%, Span1 < 2.5 and Span2 < 1.5.

[0009] Wherein, Span1 = the particle size at which the cumulative distribution of the system reaches 99% / the particle size at which the cumulative distribution of the system reaches 50%;

[0010] Span2 = (Particle size that accounts for 90% of the cumulative distribution in the system - Particle size that accounts for 10% of the cumulative distribution in the system) / 50% of the particle size;

[0011] The sphere damage rate is the percentage of spheres with surface damage diameter greater than 100 nanometers in the images formed by randomly selecting 5 positions under a scanning electron microscope at a specified magnification. If the circular area of ​​the sphere in the SEM image is greater than 70%, it is included in the total number of spheres.

[0012] The specified magnification factor refers to the magnification factor corresponding to different particle sizes. Specifically, the particle size satisfies 2µm ≤ D. 50 For particles <4µm, a scanning electron microscope needs to be magnified 5000 times; the particle size must satisfy 4µm ≤ D. 50 For particles <10µm, a scanning electron microscope needs to be magnified 2000 times; the particle size must satisfy 10µm ≤ D. 50 If the particle size is <15um, the scanning electron microscope needs to be magnified 1000 times; if the particle size meets the condition 15um≤D50<20um, the scanning electron microscope needs to be magnified 500 times.

[0013] The aforementioned surface damage refers to the non-smoothness of the sphere observed under a scanning electron microscope, which includes depressions, missing pieces, and grooves.

[0014] A diameter greater than 100 nanometers refers to a sphere with surface damage where the longest straight-line distance between missing, grooved, or recessed parts is greater than 100 nanometers.

[0015] The number of spheres with a diameter greater than 100 nanometers is defined as follows: if there is a single damaged section on the surface of the sphere with a longest straight-line distance greater than 100 nm, it is counted as 1.

[0016] In an optional implementation, Span1 < 2.0; preferably, Span2 < 1.1;

[0017] Preferably, the whiteness is >88%, and more preferably, the whiteness is >92%.

[0018] Preferably, the particle size D 50 The value is 2-20 micrometers, preferably, D 50 It is 3-10 micrometers in size.

[0019] Secondly, the present invention provides a method for preparing the large-particle-size spherical silica described in the foregoing embodiments, comprising: sequentially debinding, dispersing, calcining, and ultrafine processing of polysiloxane microspheres.

[0020] The temperature for debinding is 400℃-800℃, and the temperature for calcination is 850℃-1100℃.

[0021] In an optional embodiment, the glue removal step includes: heating to 400℃-800℃ at a heating rate of 0.5℃ / min-5℃ / min and holding at that temperature for 6 hours-10 hours, followed by cooling at a cooling rate of 10℃ / min-20℃ / min.

[0022] Preferably, the temperature is lowered to below 60°C.

[0023] In an optional embodiment, the calcination step includes: heating to 850°C-1100°C at a heating rate of 5°C / min-10°C / min and holding at that temperature for 6-20 hours, followed by cooling at a cooling rate of 10°C / min-20°C / min.

[0024] Preferably, the temperature is lowered to below 60°C.

[0025] In an optional implementation, dispersion includes mechanical agitation and crushing;

[0026] Preferably, the rotation speed of the mechanical stirring and crushing is 15Hz-40Hz; more preferably 30Hz.

[0027] In an optional embodiment, the dispersion further includes the addition of a modifier;

[0028] The mass ratio of the polysiloxane microspheres to the modifier is 150-300:1; preferably 200:1.

[0029] In an optional embodiment, the modifier is an inorganic dispersant with a particle size of 10-50 nm.

[0030] In an optional embodiment, the modifier is 10-30 nm inorganic nanoparticles.

[0031] Thirdly, the present invention provides a copper-clad laminate comprising the large-particle-size spherical silicon dioxide described in the foregoing embodiments.

[0032] The present invention has the following beneficial effects: The embodiments of the present invention provide a large-diameter spherical silica with an undamaged surface, which greatly reduces interfacial loss, significantly improves the dielectric properties of silica, and reduces dielectric loss. This spherical silica can be obtained through a process of debinding, dispersing, calcining, and ultrafine processing of polysiloxane microspheres. This process also improves the problem of sphere adhesion caused by multiple sintering processes. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a SEM image of the large-particle-size spherical silica provided in Example 1 of the present invention;

[0035] Figure 2 This is a SEM image of silicon dioxide provided in Comparative Example 1 of the present invention;

[0036] Figure 3 The SEM image provided for the definition of ball damage in this embodiment of the invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0038] In a first aspect, the present invention provides a method for preparing large-particle-size spherical silica, comprising:

[0039] S1, glue removal;

[0040] The polysiloxane microspheres are degelatinated. The polysiloxane microspheres are chemically synthesized and can be purchased directly or synthesized in-house.

[0041] The temperature for discharging the glue is 400℃-800℃, for example, any value between 400℃ and 800℃, such as 400℃, 500℃, 600℃, 700℃ and 800℃.

[0042] Specifically, a muffle furnace is used for heating and debinding. Specifically, polysiloxane microspheres are placed in the muffle furnace sagger, and the material is stacked to a height of 3-8cm in the sagger. The high-temperature furnace is inlet air via an induced draft fan, and three curves are set: heating section, heat preservation section and cooling section.

[0043] Specifically, the temperature is increased to 400℃-800℃ at a heating rate of 0.5℃ / min-5℃ / min and held for 6-10 hours. Then, the temperature is reduced at a cooling rate of 10℃ / min-20℃ / min, for example, to below 60℃. The cooling section uses cold air for rapid cooling.

[0044] The above-mentioned temperature for debinding in this embodiment of the invention enables the polysiloxane microspheres to undergo a chemical reaction, resulting in the decomposition of organic matter into silica powder. Simultaneously, this temperature prevents large-scale agglomeration of the silica powder, allowing it to disperse and, after calcination, form a complete spherical silica product. If the debinding temperature is too high, the formed silica powder will agglomerate and clump, damaging its surface morphology in subsequent processes, thereby increasing interfacial losses and the dielectric loss of the finished silica product. However, if the temperature is too low, the organic matter will not decompose or will decompose incompletely.

[0045] S2, Dispersion;

[0046] The crude silica formed by debinding is then dispersed. Dispersion allows the silica to be more dispersed, resulting in better properties for the silica formed during subsequent calcination. Specifically, dispersion is achieved by mechanical stirring and crushing. Preferably, a modifier is added during mechanical stirring to further promote dispersion. The added modifier is a nano-sized powder that provides physical isolation.

[0047] Specifically, the mechanical stirring and crushing speed provided in this embodiment of the invention is 15Hz-40Hz; preferably 30Hz. The stirring time is 10-30min, and the temperature is room temperature (e.g., 20-30℃).

[0048] The modifier used is an inorganic dispersant, such as 10-30 nm inorganic nanoparticles. The mass ratio of the polysiloxane microspheres to the modifier is 150-300:1; preferably 200:1. Under the action of a high-speed stirrer, the inorganic nanoparticles come into full contact with the material and are uniformly distributed on the surface of large-diameter micron-sized silica particles. This causes the large-diameter silica spheres to separate from each other, generating steric repulsion forces, making it difficult for large-diameter particles and particles to agglomerate and adhere. It also helps to ensure sufficient contact with oxygen during subsequent calcination. For example, inorganic nanoparticles include, but are not limited to, fumed silica.

[0049] S3, calcination;

[0050] The crushed material is calcined at a temperature of 850℃-1100℃, such as any value between 850℃ and 1100℃, for example, 850℃, 900℃, 950℃, 1000℃, 1050℃ and 1100℃.

[0051] Specifically, the temperature is increased to 850℃-1100℃ at a heating rate of 5℃ / min-10℃ / min and held for 6-20 hours. Then, the temperature is decreased at a cooling rate of 10℃ / min-20℃ / min, for example, to below 60℃.

[0052] Calcination at the above temperature can remove residual carbon from the crushed material, improve the whiteness of the finished silica product, increase the strength of the silica, and ensure that the surface of the finished silica product is intact after calcination.

[0053] S4, Ultrafine

[0054] The calcined material is then subjected to gas dispersion and ultrafine grinding in a gas mill to break up the agglomerated material after calcination. The crushing gas pressure is 0.2 MPa.

[0055] Secondly, the present invention provides a large-particle-size spherical silica, which is obtained by the preparation method of the large-particle-size spherical silica described in the foregoing embodiments.

[0056] D of large-particle-size spherical silica 50 The size is 2-20 micrometers; D is preferred. 50 The particle size is 3-10 micrometers. The whiteness of large-particle spherical silica is >88%, preferably >92%.

[0057] Furthermore, for large-diameter spherical silica, Span1 < 2.5, preferably Span1 < 2.0, and Span2 < 1.5, preferably Span2 < 1.1. The sphere loss rate is < 20%.

[0058] Wherein, Span1 = the particle size at which the cumulative distribution of the system reaches 99% / the particle size at which the cumulative distribution of the system reaches 50%.

[0059] Span2 = (Particle size accounting for 90% of the cumulative distribution in the system - Particle size accounting for 10% of the cumulative distribution in the system) / 50% of the particle size.

[0060] The sphere damage rate is the percentage of spheres with surface damage diameter greater than 100 nanometers in the images formed by randomly selecting 5 positions under a scanning electron microscope at a specified magnification. If the circular area of ​​the sphere in the SEM image is greater than 70%, it is included in the total number of spheres.

[0061] Specifically, the magnification factors corresponding to different particle sizes are as follows:

[0062] Particle size / micrometer Magnification 2≤D50＜4 5000 4≤D50＜10 2000 10≤D50＜15 1000 15≤D50＜20 500

[0063] The aforementioned surface damage refers to the non-smoothness of the sphere observed under a scanning electron microscope, which includes depressions, defects, and grooves, for example, see [link to example]. Figure 3 .

[0064] A diameter greater than 100 nanometers refers to a sphere with surface damage where the longest straight-line distance of any missing, groove, or depression is greater than 100 nanometers. (See, for example...) Figure 3 .

[0065] The number of spheres with a diameter greater than 100 nanometers is defined as follows: if the longest straight-line distance of any damaged part on the surface of the sphere is greater than 100 nm, it is counted as 1.

[0066] Damage to the surface of the sphere increases the specific surface area, thereby increasing the interfacial area between the silica sphere and the resin phase. The interface between different phases is often where charge accumulates, which can easily lead to leakage current and polarization reversal. Therefore, increasing the interfacial area will increase the interfacial loss between the two phases, thereby increasing the dielectric loss.

[0067] The preparation method provided in this invention yields large-diameter spherical silica with an undamaged surface, significantly reducing interfacial loss and greatly improving the dielectric properties of silica while reducing dielectric loss. Furthermore, this spherical silica can be obtained through a process of debinding, dispersing, calcining, and ultrafine processing of polysiloxane microspheres. This process also improves the problem of sphere adhesion caused by multiple sintering processes.

[0068] The whiteness tester selected is the Yuefeng Digital Display Whiteness Meter SBDY-1.

[0069] Meanwhile, the particle size of this invention was tested using a Malvern MS2000 laser particle size analyzer.

[0070] The dielectric loss test of this invention was performed using a network analyzer. The test sample was a mixture of powder and paraffin, with a powder content of 66% and a pellet size of Φ11.97×6.03mm. The test was conducted in resonant mode TE011.

[0071] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0072] Example 1

[0073] This invention provides a method for preparing large-particle-size spherical silica, comprising:

[0074] S1, glue removal;

[0075] The chemically formed polysiloxane microspheres (purchased from Changxing Chemical) were placed in a crucible made of corundum mullite. The material was stacked to a height of 4 cm in the crucible and placed in a high-temperature furnace to remove the glue. The temperature was increased to 600°C at a rate of 3°C / min and held for 6 hours. Then, the temperature was reduced to room temperature at a rate of 15°C / min.

[0076] S2, Dispersion;

[0077] The dispersion was carried out using a high-speed mixer and the addition of a modifier. The high-speed mixer speed was 30Hz, the mass ratio of material to modifier was 200:1, the process was carried out at room temperature, the stirring time was 20 minutes, and the modifier was 10-30nm fumed silica.

[0078] S3, calcination;

[0079] The crushed material was calcined in a muffle furnace, heated to 950°C at a heating rate of 5°C / min, and held at that temperature for 8 hours. Then, it was cooled to room temperature at a cooling rate of 15°C / min.

[0080] S4, Ultrafine

[0081] The calcined material was then subjected to an air jet mill for ultrafine grinding, with the crushing air pressure set to 0.2 MPa.

[0082] Examples 2-5

[0083] Examples 2-5 provide methods for preparing large-particle-size spherical silica. These methods are basically the same as those provided in Example 1 in terms of operation and conditions, with the only difference being some conditions, as detailed in the table below:

[0084] plan Distributed method Example 2 High-speed mixer speed 20HZ Example 3 High-speed mixer 40HZ Example 4 High-speed mixer 30Hz, no modifiers added. Example 5 High-speed mixer at 30Hz, material to modifier ratio 150:1

[0085] Examples 6-8

[0086] Examples 6-8 provide a method for preparing large-particle-size spherical silica. This method is essentially the same as the method provided in Example 1 in terms of operation and conditions, with the only difference being some of the conditions, as detailed below:

[0087] Example 6: Debinding: The temperature was increased to 400°C at a heating rate of 0.5°C / min and kept at that temperature for 10 hours. Then, the temperature was decreased to room temperature at a cooling rate of 20°C / min.

[0088] Dispersion: High-speed mixer speed 15Hz, mixing time 10min.

[0089] Calcination: Heat to 850℃ at a heating rate of 10℃ / min and hold for 20 hours, then cool down at a cooling rate of 20℃ / min to room temperature.

[0090] Example 7: Debinding: The temperature was increased to 800°C at a heating rate of 5°C / min and kept at that temperature for 8 hours. Then, the temperature was decreased to room temperature at a cooling rate of 10°C / min.

[0091] Dispersion: High-speed mixer speed 40Hz, mixing time 30min.

[0092] Calcination: Heat to 1100℃ at a heating rate of 8℃ / min and hold for 6 hours, then cool down at a cooling rate of 10℃ / min to room temperature.

[0093] Example 8: Debinding: The temperature was increased to 750°C at a heating rate of 2.5°C / min and kept at that temperature for 8 hours. Then, the temperature was decreased to room temperature at a cooling rate of 12°C / min.

[0094] Dispersion: Mixer speed 35Hz, mixing time 25min.

[0095] Calcination: Heat to 1000℃ at a heating rate of 8℃ / min and hold for 15 hours, then cool down at a cooling rate of 13℃ / min to room temperature.

[0096] Comparative Example 1

[0097] This comparative example provides a method for preparing silicon dioxide, including:

[0098] Chemically formed polysiloxane microspheres were placed in a crucible made of corundum-mullite. The material was stacked to a height of 4 cm in the crucible and calcined in a high-temperature furnace. The temperature was increased to 600°C at a rate of 3°C / min and held for 6 hours. The temperature was then decreased to room temperature at a rate of 15°C / min. Next, the temperature was increased directly from room temperature to 950°C at a rate of 5°C / min and held for 8 hours. This was followed by a decrease in temperature to room temperature at a rate of 15°C / min, and then ultrafine processing. It can be seen that Comparative Example 1 differs from Example 1 only in that the dispersion step (S2) was omitted.

[0099] Comparative Example 2

[0100] This comparative example provides a method for preparing silicon dioxide, including:

[0101] The chemically formed polysiloxane microspheres were heated in a high-temperature furnace. Specifically, the temperature was increased from room temperature to 600°C at a rate of 3°C / min, held at this temperature for 6 hours, and then the microspheres were cooled to room temperature at a rate of 15°C / min. The modifier was added to the microspheres at a mass ratio of 200:1 (material to modifier), and the mixture was manually shaken to mix. Next, the temperature was increased directly from 600°C to 950°C at a rate of 5°C / min, held for 8 hours, and then cooled to room temperature at a rate of 15°C / min. The microspheres were then ultra-finely processed. It can be seen that the difference between this comparative example and Example 1 is that high-speed stirring was not performed during dispersion in S2; only the modifier was added.

[0102] Comparative Example 3

[0103] This comparative example provides a method for preparing silicon dioxide, including:

[0104] Chemically formed polysiloxane microspheres were placed in a crucible made of corundum-mullite. The material was stacked to a height of 4 cm in the crucible and placed in a high-temperature furnace for debinding. The temperature was increased to 850°C at a rate of 3°C / min and held for 6 hours. Then, the temperature was decreased to room temperature at a rate of 15°C / min. Dispersion was achieved using a high-speed mixer at 30 Hz, with a material-to-modifier mass ratio of 200:1. The mixture was stirred at room temperature for 20 minutes. The modifier was 10-30 nm fumed silica. The crushed material was then calcined in a muffle furnace, increased to 950°C at a rate of 5°C / min and held for 8 hours. Then, the temperature was decreased to room temperature at a rate of 15°C / min and further calcined. The resulting material was then ultrafine-processed. It can be seen that the difference between this comparative example and Example 1 is the debinding temperature of 850°C.

[0105] Comparative Example 4

[0106] This comparative example provides a method for preparing silicon dioxide, including:

[0107] Chemically formed polysiloxane microspheres were placed in a crucible made of corundum-mullite. The material was stacked to a height of 4 cm in the crucible and placed in a high-temperature furnace for debinding. The temperature was increased to 350°C at a rate of 3°C / min and held for 6 hours. Then, the temperature was decreased to room temperature at a rate of 15°C / min. Dispersion was achieved using a high-speed mixer at 30 Hz, with a material-to-modifier mass ratio of 200:1. The mixture was stirred at room temperature for 20 minutes. The modifier was 10-30 nm fumed silica. The crushed material was then calcined in a muffle furnace, increased to 950°C at a rate of 5°C / min and held for 8 hours. Then, the temperature was decreased to room temperature at a rate of 15°C / min and further calcined. The resulting material was then ultrafine-processed. It can be seen that the difference between this comparative example and Example 1 is the debinding temperature of 350°C.

[0108] Characterization

[0109] The silica obtained in Example 1 and Comparative Example 1 was analyzed by SEM, and the results are shown in [reference needed]. Figures 1 to 2 .

[0110] according to Figures 1 to 2 It can be seen that the silica surface prepared by the preparation method provided in the embodiments of the present invention is undamaged, while the silica surface formed after changing the preparation method is broken.

[0111] Test case

[0112] The silica obtained in Examples 1-8 and Comparative Examples 1-4 was tested, and the results are shown in the table below.

[0113]

[0114]

[0115] Based on the above results, it can be seen that in Comparative Example 2, only dispersant was added and manually shaken to mix, with other conditions unchanged, the ball loss rate increased from 3% to 70%. This indicates that adding only dispersant to mix results in poor mixing effect between the dispersant and the material, and the material is not evenly dispersed. There are still a large number of agglomerates inside, which causes calcination adhesion and breakage.

[0116] Comparative Example 3 showed that when the glue removal temperature was increased to 850℃, with other conditions remaining unchanged, the ball loss rate increased from 3% to 85%. This indicates that when the glue removal temperature was too high, the organic matter decomposed rapidly, causing the balls to stick together after the glue was removed. Therefore, the glue removal temperature should not be too high.

[0117] In Comparative Example 4, with a glue removal temperature of 350℃ and other conditions remaining unchanged, the ball loss rate increased from 3% to 43%. This was because the glue removal temperature was too low and failed to reach the decomposition temperature of organic matter. In other words, a large amount of organic matter remained after glue removal, and the undecomposed organic matter underwent violent decomposition during subsequent calcination, causing adhesion and breakage.

[0118] Examples 1, 2, and 3 verify the effect of high-speed mixer speed on ball loss rate: When the mixer speed is reduced, the dispersion effect decreases, and the modifier and material are not completely dispersed, resulting in some material sticking together. Subsequent calcination and caking lead to a decrease in ball loss rate; When the mixer speed is too high, the modifier and material are dispersed more completely, but mechanical stress causes some balls to break on the surface, resulting in a decrease in ball loss rate.

[0119] Examples 1, 4, and 5 verify the effect of the modifier on the ball loss rate: Compared with Example 1, Example 4 was a dispersion without the addition of the modifier, while Example 5 increased the amount of modifier. The experimental results show that the ball loss rate increased from 3% to 15% without the addition of the modifier, and the dispersion effect was average; while increasing the amount of modifier did not significantly change the ball loss rate, but increased the cost.

[0120] The above examples show that the higher the sphere loss rate of the obtained silicon dioxide, the higher the dielectric loss in the pressing test. This is because sphere breakage increases the specific surface area, thereby increasing the interface area between the silicon dioxide spheres and the resin phase. The interface between different phases is often where charge accumulates, which can easily lead to leakage current and polarization reversal. Therefore, increasing the interface area will increase the interface loss between the two phases, thereby increasing the dielectric loss.

[0121] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A type of large-particle-size spherical silica, characterized in that, The large-diameter spherical silica particles meet the following requirements: sphere loss rate < 20%, Span1 < 2.5 and Span2 < 1.

5. Wherein, Span1 = the particle size at which the cumulative distribution of the system reaches 99% / the particle size at which the cumulative distribution of the system reaches 50%; Span2 = (Particle size that accounts for 90% of the cumulative distribution in the system - Particle size that accounts for 10% of the cumulative distribution in the system) / 50% of the particle size; The sphere damage rate is the percentage of spheres with surface damage diameter greater than 100 nanometers in the images formed by randomly selecting 5 positions under a scanning electron microscope at a specified magnification. If the circular area of ​​the sphere in the SEM image is greater than 70%, it is included in the total number of spheres. The specified magnification factor refers to the magnification factor corresponding to different particle sizes. Specifically, the particle size satisfies 2µm ≤ D. 50 For particles <4µm, a scanning electron microscope needs to be magnified 5000 times; the particle size must satisfy 4µm ≤ D. 50 For particles <10µm, a scanning electron microscope needs to be magnified 2000 times; the particle size must satisfy 10µm ≤ D. 50 If the particle size is <15um, the scanning electron microscope needs to be magnified 1000 times; if the particle size meets the condition 15um≤D50<20um, the scanning electron microscope needs to be magnified 500 times. The method for preparing the large-particle-size spherical silica includes: sequentially debinding, dispersing, calcining, and ultrafine processing of polysiloxane microspheres, wherein the debinding temperature is 400℃-800℃, and the calcination temperature is 850℃-1100℃; wherein the dispersion includes mechanical stirring and crushing.

2. The large-particle-size spherical silica according to claim 1, characterized in that, Span1 < 2.

0.

3. The large-particle-size spherical silica according to claim 1, characterized in that, Span2<1.

1.

4. The large-particle-size spherical silica according to claim 1, characterized in that, The whiteness of the large-particle-size spherical silica is >88%.

5. The large-particle-size spherical silica according to claim 1, characterized in that, The whiteness of the large-particle-size spherical silica is >92%.

6. The large-particle-size spherical silica according to claim 1, characterized in that, The particle size D of the large-diameter spherical silica 50 It ranges from 2 to 20 micrometers.

7. The large-particle-size spherical silica according to claim 1, characterized in that, The particle size D of the large-diameter spherical silica 50 It is 3-10 micrometers in size.

8. The large-particle-size spherical silica according to claim 1, characterized in that, The glue removal process includes: heating to 400℃-800℃ at a heating rate of 0.5℃ / min-5℃ / min and holding at that temperature for 6-10 hours, followed by cooling at a cooling rate of 10℃ / min-20℃ / min.

9. The large-particle-size spherical silica according to claim 8, characterized in that, The temperature will drop below 60°C.

10. The large-particle-size spherical silica according to claim 1, characterized in that, The calcination process includes: heating to 850℃-1100℃ at a heating rate of 5℃ / min-10℃ / min and holding at that temperature for 6-20 hours, followed by cooling at a cooling rate of 10℃ / min-20℃ / min.

11. The large-particle-size spherical silica according to claim 10, characterized in that, The temperature will drop below 60°C.

12. The large-particle-size spherical silica according to claim 1, characterized in that, The rotation speed of mechanical mixing and crushing is 15 Hz - 40 Hz.

13. The large-particle-size spherical silica according to claim 1, characterized in that, The mechanical stirring and crushing speed is 30Hz.

14. The large-particle-size spherical silica according to claim 1, characterized in that, Dispersion also includes the addition of modifiers; The mass ratio of the polysiloxane microspheres to the modifier is 150-300:

1.

15. The large-particle-size spherical silica according to claim 14, characterized in that, The mass ratio of the polysiloxane microspheres to the modifier is 200:

1.

16. The large-particle-size spherical silica according to claim 14, characterized in that, The modifier is an inorganic nanoparticle of 10-30 nm.

17. A copper-clad laminate, characterized in that, It includes the large-particle-size spherical silica as described in claim 1.

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