Black spherical silicon and preparation method and application thereof

Abstract

The invention discloses black spherical silicon as well as a preparation method and application thereof, and relates to the technical field of copper-clad plates. The black spherical silicon provided by the embodiment of the invention has a core-shell structure, a shell layer is a silicon dioxide layer, a core layer is an amorphous silicon dioxide composite material, and the black spherical silicon can give consideration to dielectric loss and peel strength by regulating and controlling the content of surface active groups under unit mass to meet a specific range; and the thickness of the silicon dioxide of the shell layer accounts for 0.4-12% of the overall size, so that the absorption capacity of the powder to ultraviolet light is controlled, the reflective rate R is less than or equal to 10%, and the withstand voltage is greater than or equal to 5KV. The black spherical silicon provided by the invention has the characteristics of low dielectric loss and low reflective rate, and can reduce dielectric loss, reduce signal attenuation and improve stability after being used for a copper-clad plate.

Description

Technical Field

[0001] This invention relates to the field of copper clad laminate technology, and more specifically, to black spherical silicon, its preparation method, and its application. Background Technology

[0002] As end-product usage frequency increases, the dielectric loss requirements for copper-clad laminates (CCLs) are also rising. During PCB etching, the unavoidable reflection of the board's color at the etching locations causes jagged edges in the etching, resulting in higher dielectric loss. To address this, a small amount of carbon black is typically added to the CCL to adjust its color and reduce light reflection. However, carbon black is conductive, increasing the board's conductivity and thus its dielectric loss.

[0003] The dielectric loss of copper-clad laminates (CCLs) mainly consists of the dielectric loss of the materials themselves and the interfacial loss, i.e., the dielectric loss of each component material and the dielectric loss generated at the interfaces between them. Therefore, preparing low-dielectric-loss CCLs requires not only low dielectric loss of the raw materials themselves but also low interfacial loss between the raw materials and the resin. Consequently, the fillers used typically undergo surface treatment. Conventional chemically processed silica spheroids require high-temperature treatment, where the active hydroxyl groups on the surface undergo dehydration and condensation, resulting in silica with low hydroxyl content and low reaction efficiency with silane coupling agents. However, without high-temperature treatment or by adding deionized water for hydrolysis during modification, the silica surface will have an excessively high hydroxyl content. Due to intermolecular forces and steric hindrance, the reacting silane coupling agent cannot consume all the hydroxyl groups, and the excess polar hydroxyl groups increase the dielectric loss of the powder.

[0004] Therefore, it is of great significance to prepare a black spherical silicon with low dielectric loss and low reflectivity.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide black spherical silicon with low dielectric loss and low reflectivity, as well as its preparation method and application, with the aim of providing black spherical silicon with low dielectric loss and low reflectivity.

[0007] This invention is implemented as follows:

[0008] In a first aspect, the present invention provides black spherical silicon, which has a core-shell structure, wherein the shell layer is a silicon dioxide layer and the core layer is an amorphous silicon dioxide composite material; the ratio of the thickness of the shell layer to the diameter of the black spherical silicon is (0.4-12):100.

[0009] Define the density of active groups in the shell as X, where X = P / S SSA , 0.0005 < X < 0.0050;

[0010] P represents the content of surface-active groups per unit mass, without units;

[0011] S SSA The specific surface area of ​​the powder is expressed in m². 2 / g.

[0012] In an optional embodiment, the test method for P is as follows: 4g of alkyl coupling agent KBM-13 and 200g of black spherical silica are added to an ethanol solvent and allowed to stand for 48 hours; the powder after standing is filtered, and the lower clear solution is collected and recorded as mass M. 总 The mass fraction of the silane coupling agent in the lower clear solution was then determined by liquid chromatography and recorded as W. 甲 ; P = (4 - M) was calculated using the formula. 总 ×W 甲 ) / 200.

[0013] In an optional implementation, the value of P is 0.0006-0.0039.

[0014] In an optional implementation, S SSA The value is 0.60m. 2 / g-7.00m 2 / g;

[0015] And / or, the black spherical silicon meets the following requirements: withstand voltage ≥ 5KV, reflectivity R ≤ 10%.

[0016] In an optional implementation, the black spherical silicon satisfies the following condition: dielectric loss Df ≤ 0.005;

[0017] And / or, the average particle size of the black spherical silicon is 0.5 μm-5.0 μm.

[0018] Secondly, the present invention provides a method for preparing black spherical silicon according to the aforementioned embodiments, comprising:

[0019] The spherical silica obtained by hydrolysis of organosilicon is calcined in a furnace.

[0020] The calcination includes a first calcination stage and a second calcination stage.

[0021] During the second calcination stage, the dew point temperature of the humidification tank is controlled between 20℃ and 80℃.

[0022] In an optional embodiment, the first calcination stage is carried out in a non-oxidizing gas, with the calcination temperature controlled at 600℃-1200℃ and the holding time at 1h-5h.

[0023] And / or, the calcination temperature in the second calcination stage is controlled at 800℃-1100℃, and the holding time is 1h-5h.

[0024] In an optional embodiment, the method further includes: surface treatment with a silane coupling agent after calcination;

[0025] The process of surface treatment using silane coupling agent includes: mixing and stirring the calcined powder with silane coupling agent, and then keeping it at 110℃-140℃ for 0.5h-12h.

[0026] The mass ratio of silane coupling agent to calcined powder is (0.2-1.0):100.

[0027] In an optional embodiment, the preparation process of spherical silica includes: hydrolyzing and condensing an organosilane;

[0028] Preferably, the preparation process of the spherical silica includes: mixing an organosilane with water or an acid to obtain a mixture, and reacting the mixture with an organic base or an inorganic base;

[0029] More preferably, the mixture is mixed with sodium hydroxide solution and reacted at 30°C-60°C for 1-3 hours;

[0030] Preferably, the organosilicon is selected from at least one of the following organotrimethoxysilanes: methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane, methyltripropoxysilane, ethyltripropoxysilane, propyltripropoxysilane, butyltripropoxysilane, etc.

[0031] Thirdly, the present invention provides a copper-clad laminate, comprising any of the black spherical silicon in the foregoing embodiments or black spherical silicon prepared by any of the preparation methods in the foregoing embodiments.

[0032] The present invention has the following beneficial effects: The black spherical silicon provided in the embodiments of the present invention has a core-shell structure, with a shell layer of silicon dioxide and a core layer of amorphous silicon dioxide composite material. By controlling the content of surface active groups per unit mass to meet a specific range, the black spherical silicon can balance dielectric loss and reflectivity. The thickness of the shell silicon dioxide accounts for 0.4% to 12% of this size, thereby controlling the absorption capacity of the powder to ultraviolet light, meeting the requirements of reflectivity R≤10% and withstand voltage≥5KV. The black spherical silicon provided by the present invention has the characteristics of low dielectric loss and low reflectivity. When used in copper-clad laminates, it can reduce dielectric loss, giving the board higher signal transmission efficiency and better signal transmission stability.

[0033] The preparation method provided in this invention employs a rotary calcination furnace with a controllable gas atmosphere, ensuring uniform heating of the powder. By adjusting the dew point temperature of the humidification tank, the moisture content in the nitrogen gas can be quantitatively controlled. At high temperatures, the moisture in the nitrogen gas preferentially consumes carbon on the powder surface, forming a dense silica layer. Simultaneously, excess moisture activates the silica surface, allowing it to retain an appropriate number of active sites at high temperatures. Because the black spherical silicon contains a certain amount of hydroxyl groups on its surface, it readily reacts with silane coupling agents to obtain monodisperse, highly cohesive black spherical silicon powder, resulting in an overall dielectric loss Df of ≤0.005 for the substrate. Attached Figure Description

[0034] 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.

[0035] Figure 1 This is a schematic diagram of the black spherical silicon structure;

[0036] Figure 2 A scanning electron microscope image of the cross-section of black spherical silicon prepared in Example 1;

[0037] Figure 3 The reflectance R value in the ultraviolet region of the black spherical silicon prepared in Example 1. Detailed Implementation

[0038] 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.

[0039] This invention provides a black spherical silicon, such as... Figure 1 As shown, the black spherical silicon exhibits a core-shell structure, with a shell layer of silicon dioxide and a core layer of amorphous silicon dioxide composite material. The so-called "amorphous silicon dioxide composite material" is a composite material formed by uniformly doping carbon atoms into amorphous silicon dioxide.

[0040] The ratio of the shell thickness to the diameter of the black spherical silicon is (0.4-12):100. The density of active groups in the shell is defined as X, where X = P / S. SSA 0.0005 < X < 0.0050; P represents the content of surfactant groups per unit mass, without unit; S SSA The specific surface area of ​​the powder is expressed in m².2 / g.

[0041] Specifically, the ratio of the shell thickness to the diameter of the black spherical silicon can be 0.4:100, 1.0:100, 3.0:100, 5.0:100, 8.0:100, 10.0:100, 12.0:100, etc. The value of the active group density X of the shell can be 0.0006, 0.0008, 0.0010, 0.003, 0.005, etc.

[0042] It should be noted that when the density X of active groups in the shell is too small, the limited number of active sites results in less silane coupling agent that can react, leading to weak bonding with the resin and poor peel strength. Furthermore, due to steric hindrance and mutual repulsion, the amount of silane coupling agent that can react is limited. When the density X of active groups in the shell is too large, only a portion of the active groups are reacted. The unreacted active groups, being polar, will experience polarization losses in the electric field, resulting in higher dielectric loss in the copper-clad laminate. Controlling the density X of active groups in the shell within the range defined in this invention balances dielectric loss, peel strength, and reflectivity.

[0043] In some embodiments, the method for testing P in the formula for calculating the density of active groups X of the shell is as follows: (1) Add 4g of alkyl coupling agent KBM-13 and 200g of black spherical silicon to ethanol solvent and let stand for 48 hours; (2) Filter the powder after standing, collect the lower clear solution, and record it as mass M. 总 (3) Then, the mass fraction of the silane coupling agent in the lower clear solution was determined by liquid chromatography and recorded as W. 甲 (4) Calculate P = (4 - M) using the formula. 总 ×W 甲 ) / 200.

[0044] The black spherical silicon provided in this embodiment of the invention satisfies the following condition: the content P of surface active groups per unit mass is 0.0006-0.0039, such as 0.0006, 0.0010, 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0039, etc. SSA The value is 0.60m. 2 / g-7.00m 2 / g, such as 0.60m 2 / g, 1.00m 2 / g, 2.00m 2 / g, 3.00m 2 / g, 4.00m 2 / g, 5.00m 2 / g, 6.00m 2 / g, 7.00m 2 / g.

[0045] The black spherical silicon provided in this invention meets the following requirements: reflectivity R ≤ 10%, withstand voltage ≥ 5KV, and is a black spherical silicon with low dielectric loss and low reflectivity. Specifically, the reflectivity R of the black spherical silicon can be 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, etc. The withstand voltage of the black spherical silicon can be 5KV, 6KV, 7KV, 8KV, 9KV, 10KV, etc.

[0046] In some embodiments, the black spherical silicon is modified with a silane coupling agent to achieve a dielectric loss Df ≤ 0.005, such as 0.005, 0.004, 0.003, 0.002, 0.001, etc. When this black spherical silicon is used in copper-clad laminates, it can reduce dielectric loss, making the laminate less prone to short circuits.

[0047] In some embodiments, the black spherical silicon particles have a uniform particle size with an average particle size of 0.5μm-5.0μm, such as 0.5μm, 1.0μm, 2.0μm, 3.0μm, 4.0μm, 5.0μm, etc.

[0048] This invention also provides a method for preparing black spherical silicon, comprising the following steps:

[0049] S1. Preparation of spherical silica

[0050] The preparation process of spherical silica includes: hydrolyzing and condensing organosilanes. The specific method of hydrolysis and condensation is not limited and existing processes can be used.

[0051] In some embodiments, the preparation process of the spherical silica includes: mixing an organosilane with water or an acid to obtain a mixture, and reacting the mixture with an organic or inorganic base. Water or acid may be added during hydrolysis, and an organic or inorganic base may be used for condensation. Preferably, the mixture is mixed with a sodium hydroxide solution and reacted at 30°C-60°C for 1-3 hours; specifically, when preparing spherical silica, the reaction temperature can be controlled at 30°C, 40°C, 50°C, 60°C, etc., and the reaction time can be 1 hour, 2 hours, 3 hours, etc.

[0052] In some embodiments, the organosilicon is selected from at least one of the following organotrialkoxysilanes: methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane, methyltripropoxysilane, ethyltripropoxysilane, propyltripropoxysilane, butyltripropoxysilane, etc., and the organosilicon can be any one or more of the above.

[0053] In some embodiments, the preparation process of the mixture includes: mixing organosilane and water and stirring at 20°C-60°C for 1-3 hours to obtain a homogeneous mixture. Specifically, the stirring temperature can be 30°C, 40°C, 50°C, 60°C, etc., and the stirring time can be 1 hour, 2 hours, 3 hours, etc.

[0054] In some embodiments, the mass ratio of organosilane to water is 1:(5-25), such as 1:5, 1:10, 1:15, 1:20, 1:25, etc.; the mass fraction of sodium hydroxide solution is 1%-3%, such as 1%, 2%, 3%, etc.; the mass ratio of the amount of sodium hydroxide solution added to the mass of organosilane is (1-5):100, such as 1:100, 2:100, 3:100, 4:100, 5:100, etc. By adjusting the amount of each raw material, the pH value of the reaction is made more suitable, and the reaction is made complete.

[0055] Furthermore, after the reaction is complete, solid-liquid separation is performed. The obtained solid material is washed and dried. The solid-liquid separation method is not limited, such as filtration. Unreacted ions are then removed by washing with water, and after drying, pure spherical silica is obtained.

[0056] S2, calcination

[0057] Spherical silica obtained from the hydrolysis of organosilicon is calcined in a furnace with a controlled gas atmosphere, such as a bell furnace. The calcination includes a first calcination stage and a second calcination stage. The type of furnace is not limited to a bell furnace; as long as the gas atmosphere can be controlled, it can also be a pusher furnace or a muffle furnace.

[0058] In some embodiments, the first calcination stage is carried out in a non-oxidizing gas environment under high-temperature, oxygen-free conditions, which rapidly carbonizes the organic matter in the raw materials and distributes it uniformly within the spheres. The calcination temperature is controlled at 600℃-1200℃, and the holding time is 1h-5h; preferably, the calcination temperature of the first calcination stage is 850℃-1100℃. Specifically, the calcination temperature of the first calcination stage can be 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, etc., and the holding time can be 1h, 2h, 3h, 4h, 5h, etc.

[0059] Furthermore, the non-oxidizing gas can be an inert gas, such as nitrogen or argon.

[0060] Furthermore, in the second calcination stage, the dew point temperature of the humidification tank is controlled between 20℃ and 80℃, such as 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, etc. The thickness of the silica layer and the internal carbon layer is controlled by adjusting the quality of moisture during calcination using an atmosphere chamber.

[0061] It should be noted that the moisture content in the nitrogen gas can be quantitatively controlled by adjusting the dew point temperature of the humidification tank. At high temperatures, the moisture in the nitrogen gas preferentially consumes carbon on the powder surface, forming a dense silica layer. Simultaneously, excess moisture also activates the silica surface, ensuring it retains a suitable number of active sites at high temperatures. Because this black spherical silica contains a certain amount of hydroxyl groups on its surface, it readily reacts with silane coupling agents to obtain monodisperse, highly cohesive black spherical silica powder, resulting in an overall dielectric loss Df of the board ≤ 0.005.

[0062] In a preferred embodiment, the dew point temperature is controlled at 40℃-60℃ during the second calcination stage. The mass of water reacting with carbon and the reaction time are quantitatively controlled by a bell-shaped furnace to control the thickness of the surface silica layer and the internal carbon layer, thereby controlling the powder's absorption capacity for ultraviolet light and ensuring a reflectivity R≤10% and a withstand voltage ≥5KV.

[0063] In some embodiments, the calcination temperature in the second calcination stage is controlled at 800℃-1100℃, and the holding time is 1h-5h; preferably, the calcination temperature in the second calcination stage is controlled at 1000℃-1050℃.

[0064] Specifically, the calcination temperature in the second calcination stage can be controlled at 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, etc.; the holding time can be 1h, 2h, 3h, 4h, 5h, etc.

[0065] It should be noted that by quantitatively controlling the quality of water and the reaction time with carbon using a bell furnace, the thickness of the surface silica layer can be controlled to be 0.4% to 12% of this size, thereby controlling the absorption capacity of the powder to ultraviolet light and meeting the requirements of reflectivity R≤10% and withstand voltage≥5KV.

[0066] S3, Surface Treatment

[0067] Surface treatment with a silane coupling agent results in black spherical silica with different functional groups on its surface, formed by covalent bonding. Because the density of surface active groups in this black spherical silica is controllable, the optimal density can be selected based on the silane coupling agent to achieve an overall dielectric loss Df ≤ 0.005, with a preferred value of Df ≤ 0.001.

[0068] In some embodiments, the surface treatment process using a silane coupling agent includes: mixing and stirring the calcined powder with the silane coupling agent, and then holding it at 110℃-140℃ for 0.5h-12h, preferably 1h-5h, more preferably 2h-4h. Since the carbon layer on the powder surface reacts with water, active hydroxyl groups remain on the surface, promoting the hydrolysis of the coupling agent during stirring. Under heating conditions, these hydroxyl groups react with the coupling agent through covalent bonds, resulting in black spherical silica with different functional groups on the surface. By controlling the reaction temperature and time, sufficient functional groups are introduced onto the surface of the black spherical silica, achieving a better surface modification effect. The mass ratio of the silane coupling agent to the calcined powder is (0.2-1.0):100, such as 0.2:100, 0.3:100, 0.5:100, 0.8:100, 1.0:100, etc.

[0069] Specifically, the reaction temperature with the silane coupling agent can be 110℃, 120℃, 125℃, 130℃, 135℃, 140℃, etc.; the holding time can be 0.5h, 1.0h, 2.0h, 3.0h, 4.0h, 5.0h, 8.0h, 10.0h, 12.0h, etc.

[0070] In some embodiments, the silane coupling agent comprises, but is not limited to, vinyl, alkyl, amino, aniline, and methyl methacrylate silane modifiers, and the silane coupling agent can be any one or more of the above.

[0071] This invention also provides a copper-clad laminate, including the black spherical silicon provided in this invention. By using black spherical silicon with low dielectric loss and low reflectivity, the dielectric loss can be reduced, signal attenuation can be reduced, and stability can be improved after copper-clad laminate is used.

[0072] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0073] Example 1

[0074] This embodiment provides a black spherical silicon, the preparation steps of which are as follows:

[0075] (1) Weigh organosilane (methyltriethoxysilane) and pure water into a beaker, making the ratio of silane to pure water 1:7.7. Stir at 40℃ and 300 rpm / min for 2 hours to form a homogeneous mixture. Add 3% by mass of organosilane and 2% sodium hydroxide solution with a solid content of 2%, stir for 5 minutes, let stand, and then react at 100 rpm / min and 30℃ for 1 hour. Filter the slurry, wash with water, and dry to obtain chemically produced silica spheres containing organic matter.

[0076] (2) Place the spherical silica obtained in step (1) into a furnace such as a bell furnace where the gas atmosphere can be controlled, and calcine it for 3 hours at 950°C under a nitrogen atmosphere. Then, open the humidification tank and set the dew point temperature to 50°C, and calcine it for 3 hours at 1030°C.

[0077] (3) The calcined powder from step (2) is added to a high-speed mixer and stirred at 30 Hz until the temperature is raised to 110°C and held for 10 min. Then the speed is reduced to 20 Hz, and the silane modifier (KBM-503) is slowly added. The speed is increased to 30 Hz, the temperature is raised to 130°C, and the mixture is held for 20 min before being discharged. The mass ratio of the calcined powder to the silane modifier is 100:0.2.

[0078] Example 2

[0079] This embodiment provides a black spherical silicon, the preparation steps of which differ from those of Embodiment 1 only in the operating parameters of step (2), as follows:

[0080] The spherical silica obtained in step (1) is placed in a furnace such as a bell furnace where the gas atmosphere can be controlled. It is first calcined at 600°C for 3 hours under a nitrogen atmosphere. Then, the humidification tank is opened and the dew point temperature is set to 20°C. It is then calcined at 800°C for 3 hours.

[0081] Example 3

[0082] This embodiment provides a black spherical silicon, the preparation steps of which differ from those of Embodiment 1 only in the operating parameters of step (2), as follows:

[0083] The spherical silica obtained in step (1) is placed in a furnace such as a bell furnace where the gas atmosphere can be controlled. It is first calcined at 1200°C for 3 hours under a nitrogen atmosphere. Then, the humidification tank is opened and the dew point temperature is set to 80°C. It is then calcined at 1100°C for 3 hours.

[0084] Example 4

[0085] This embodiment provides a black spherical silicon, the only difference between its preparation steps and those of Embodiment 1 is that in step (2), the humidification tank is opened and the dew point temperature is set to 40°C.

[0086] Example 5

[0087] This embodiment provides a black spherical silicon, the only difference between its preparation steps and those of Embodiment 1 is that in step (2), the humidification tank is opened and the dew point temperature is set to 60°C.

[0088] Example 6

[0089] This embodiment provides a black spherical silicon, the only difference between its preparation steps and those of Embodiment 1 is that in step (2), the humidification tank is opened and the dew point temperature is set to 20°C.

[0090] Example 7

[0091] This embodiment provides a black spherical silicon, the only difference between its preparation steps and those of Embodiment 1 is that in step (2), the humidification tank is opened and the dew point temperature is set to 80°C.

[0092] Example 8

[0093] (1) Weigh organosilane (methyltriethoxysilane) and pure water into a beaker, making the ratio of silane to pure water 1:20. Stir at 60℃ and 300 rpm / min for 2 hours to form a homogeneous mixture. Add 3% by mass of organosilane and 2% sodium hydroxide solution with a solid content of 2%, stir for 5 minutes, let stand, and then react at 200 rpm / min and 60℃ for 1 hour. Filter the slurry, wash with water, and dry to obtain chemically produced silica spheres containing organic matter.

[0094] (2) Place the spherical silica obtained in step (1) into a furnace such as a bell furnace where the gas atmosphere can be controlled, and calcine it for 3 hours at 950°C under a nitrogen atmosphere. Then, open the humidification tank and set the dew point temperature to 40°C, and calcine it for 3 hours at 1030°C.

[0095] (3) The calcined powder from step (2) is added to a high-speed mixer and stirred at 30 Hz until the temperature is raised to 110°C and held for 10 min. Then the speed is reduced to 20 Hz, and the silane modifier (KBM-503) is slowly added. The speed is increased to 30 Hz, the temperature is raised to 130°C, and the mixture is held for 20 min before being discharged. The mass ratio of the calcined powder to the silane modifier is 100:1.0.

[0096] Example 9

[0097] (1) Weigh organosilane (methyltriethoxysilane) and pure water into a beaker, making the ratio of silane to pure water 1:5.6. Stir for 2 hours at 25°C and 500 rpm / min to form a homogeneous mixture. Add 3% by weight of organosilane and 2% sodium hydroxide solution with a solid content of 2%, stir for 5 minutes, let stand, and then react for 1 hour at 25°C with a rotation speed of 100 rpm / min. Filter the slurry, wash with water, and dry to obtain chemically produced silica spheres containing organic matter.

[0098] (2) Place the spherical silica obtained in step (1) into a furnace such as a bell furnace where the gas atmosphere can be controlled, and calcine it for 3 hours at 950°C under a nitrogen atmosphere. Then, open the humidification tank and set the dew point temperature to 70°C, and calcine it for 3 hours at 1030°C.

[0099] (3) The calcined powder from step (2) is added to a high-speed mixer and stirred at 30 Hz until the temperature is raised to 110°C and held for 10 min. Then the speed is reduced to 20 Hz, and the silane modifier (KBM-503) is slowly added. The speed is increased to 30 Hz, the temperature is raised to 130°C, and the mixture is held for 20 min before being discharged. The mass ratio of the calcined powder to the silane modifier is 100:0.2.

[0100] Comparative Example 1

[0101] This comparative example provides a black spherical silicon, the preparation steps of which differ from those of Example 1 only in the operating parameters of step (2), as follows:

[0102] The spherical silica obtained in step (1) is placed in a furnace such as a bell furnace where the gas atmosphere can be controlled. It is first calcined at 500°C for 3 hours under a nitrogen atmosphere. Then, the humidification tank is opened and the dew point temperature is set to 15°C. It is then calcined at 700°C for 3 hours.

[0103] Comparative Example 2

[0104] This comparative example provides a black spherical silicon, the preparation steps of which differ from those of Example 1 only in the operating parameters of step (2), as follows:

[0105] The spherical silica obtained in step (1) is placed in a furnace such as a bell furnace where the gas atmosphere can be controlled. It is first calcined at 1300°C for 3 hours under a nitrogen atmosphere. Then, the humidification tank is opened and the dew point temperature is set to 85°C. It is then calcined at 1200°C for 3 hours.

[0106] Comparative Example 3

[0107] This comparative example provides a black spherical silicon, the only difference between its preparation steps and those of Example 1 is that: in step (2), the humidification tank is not turned on to set the dew point temperature during the second stage of calcination, and the process is carried out under the atmosphere of the first stage of calcination.

[0108] Experimental Example 1

[0109] The SEM image of the black spherical silicon obtained in Test Example 1 is shown below. Figure 2 As shown, the black spherical silicon has a core-shell structure, and the shell thickness is about 30 nm.

[0110] Experimental Example 2

[0111] The performance parameters of the black spherical silicon prepared in the examples and comparative examples were tested, and the results are shown in Table 1.

[0112] Surface silica thickness percentage: High-magnification field emission electron microscope was used after argon ion polishing.

[0113] Content of surfactant groups per unit mass P: 4g of alkyl coupling agent KBM-13 and 200g of black silica spheres were added to ethanol solvent and allowed to stand for 48 hours; the powder was filtered after standing, and the lower clear solution was collected and recorded as mass M. 总 The content of silane coupling agent in the lower clear solution was then determined by liquid chromatography and recorded as W. 甲 ; P = (4 - M) was calculated using the formula. 总 ×W 甲 ) / 200.

[0114] The specific surface area of ​​the powder was tested using a physical adsorption instrument.

[0115] The dielectric loss Df was tested using a network analyzer.

[0116] Reflectivity and voltage withstand sample preparation: (1) Weigh 15.00 g of black spherical silicon and 15.00 g of 2.5 μm spherical silicon and add them to a mortar. Add 3.75 g of 8% PVA solution and stir continuously until a uniform slurry is formed. (2) Then place it in an oven and keep it at 120℃ for 2 h. (3) Weigh 20 g of the dried powder and add it to a 40 mm diameter mold. Hold it at 30 MPa for 10 min. (4) Then use a UV spectrophotometer to test the reflectivity.

[0117] The reflectance R-value of the black spherical silicon prepared in Example 1 in the ultraviolet region was tested as follows: Figure 3 As shown.

[0118] The test results for the examples and comparative examples are shown in Table 1:

[0119] Table 1 shows the performance test results of the black spherical silicon obtained in the examples and comparative examples.

[0120]

[0121]

[0122] As shown in Table 1, the black spherical silicon prepared in the embodiments of the present invention meets the requirements of dielectric loss Df≤0.005, reflectivity R≤10%, withstand voltage ≥5KV, and average particle size of 0.5-5.0μm, and its overall performance is superior to that of the comparative examples. The shell active group density X of Comparative Examples 1 and 3 is too small, resulting in a small amount of modifier that can react, leading to poor peel strength of the product. Simultaneously, the low shell thickness, i.e., the low insulation layer thickness, leads to poor overall withstand voltage performance, increased conductivity loss, and poor dielectric loss of the copper-clad laminate. The shell active group density X of Comparative Example 2 is too large, so the coupling agent cannot consume all the active groups, and the excess active groups increase polarization loss, resulting in a higher dielectric loss compared to Example 1. Furthermore, the excessive shell thickness leads to a decrease in powder reflectivity.

[0123] Experimental Example 3

[0124] The black spherical silicon provided in this embodiment of the invention was used in copper-clad laminates. The performance of the copper-clad laminates was tested, and it showed that it had lower dielectric loss under the same light absorption.

[0125] The above are merely preferred embodiments of the present invention and are not intended to limit the present 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 black spherical silicon, characterized in that, The black spherical silicon has a core-shell structure, with a shell layer of silicon dioxide and a core layer of amorphous silicon dioxide composite material; the ratio of the thickness of the shell layer to the diameter of the black spherical silicon is (0.4-12):

100. The density of active groups in the shell is X, where X = P / S SSA 0.0005 < X < 0.0050, unit is g / m³ 2 ; P represents the content of surface-active groups per unit mass, without units; S SSA The specific surface area of ​​the powder is expressed in m². 2 / g.

2. The black spherical silicon according to claim 1, characterized in that, The test method for P is as follows: Add 4g of alkyl coupling agent KBM-13 and 200g of black spherical silica to ethanol solvent and let stand for 48 hours; filter the powder after standing, collect the lower clear solution, and record it as mass M. 总 The mass fraction of the silane coupling agent in the lower clear solution was then determined by liquid chromatography and recorded as W. 甲 ; P = (4 - M) was calculated using the formula. 总 ×W 甲 ) / 200.

3. The black spherical silicon according to claim 1, characterized in that, The value of P ranges from 0.0006 to 0.0039.

4. The black spherical silicon according to claim 1, characterized in that, S SSA The value is 0.60m 2 / g-7.00m 2 / g; And / or, the black spherical silicon satisfies the following conditions: withstand voltage ≥ 5KV, reflectivity R ≤ 10%.

5. The black spherical silicon according to claim 1, characterized in that, The black spherical silicon satisfies the following condition: dielectric loss Df ≤ 0.005; And / or, the average particle size of the black spherical silicon is 0.5 μm-5.0 μm.

6. A method for preparing black spherical silicon according to any one of claims 1-5, characterized in that, include: The spherical silica obtained by hydrolysis of organosilicon is calcined in a furnace. The calcination includes a first calcination stage and a second calcination stage; During the second calcination stage, the dew point temperature of the humidification tank is controlled between 20℃ and 80℃.

7. The preparation method according to claim 6, characterized in that, The first calcination stage is carried out in a non-oxidizing gas, with the calcination temperature controlled at 600℃-1200℃ and the holding time at 1h-5h. And / or, in the second calcination stage, the calcination temperature is controlled at 800℃-1100℃, and the holding time is 1h-5h.

8. The preparation method according to claim 6, characterized in that, Also includes: After calcination, the surface is treated with a silane coupling agent; The process of surface treatment using silane coupling agent includes: mixing and stirring the calcined powder with silane coupling agent, and then keeping it at 110℃-140℃ for 0.5h-12h. The mass ratio of the silane coupling agent to the calcined powder is (0.2-1.0):

100.

9. The preparation method according to claim 6, characterized in that, The preparation process of the spherical silica includes: hydrolyzing and condensing organosilanes; Preferably, the preparation process of the spherical silica includes: mixing an organosilane with water or an acid to obtain a mixture, and reacting the mixture with an organic base or an inorganic base; More preferably, the mixture is mixed with sodium hydroxide solution and reacted at 30°C-60°C for 1-3 hours; Preferably, the organosilicon is selected from at least one of methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, butyltriethoxysilane, methyltripropoxysilane, ethyltripropoxysilane, propyltripropoxysilane, and butyltripropoxysilane.

10. A copper-clad laminate, characterized in that, The black spherical silicon includes the black spherical silicon as described in any one of claims 1-5 or the black spherical silicon prepared by the preparation method described in any one of claims 6-9.

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