Silica, method for producing the same, composite powder, resin composition, and use thereof

Abstract

The application provides a kind of silicon dioxide and its preparation method, composite powder, resin composition and its application, it is related to the field of semiconductor packaging material.The silicon dioxide provided by the present application includes porous silica microspheres, and the porous silica microspheres have a plurality of dispersedly distributed first regions and second regions in the SEM image.The ratio of the total number of black pixels in the first region to the total number of overall pixels possessed by the porous silica microspheres is greater than 0.2, the distance between two adjacent first regions is less than 2 μm, and the first region has a longest diameter, which is less than 2 μm.By controlling the appropriate spacing and size, the silicon dioxide provided by the present application can greatly retain the mechanical strength and toughness of the material while achieving high porosity.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging materials, and in particular to silicon dioxide and its preparation method, composite powder, resin composition and its application. Background Technology

[0002] In recent years, cutting-edge application scenarios such as 5G communication, AI servers and high-speed computing have placed higher demands on low loss and high fidelity of signal transmission, making high-frequency and high-speed copper-clad laminates a key focus of current copper-clad laminate research and development.

[0003] In high-frequency, high-speed copper-clad laminates, microporous silica serves as a key functional filler, not only helping to reduce overall material costs but also effectively lowering dielectric constant and dielectric loss, thereby meeting the performance requirements of high-frequency signal transmission. To achieve even lower dielectric constants and losses, microporous silica materials typically require higher porosity; however, high-porosity microporous silica materials generally suffer from insufficient mechanical strength and toughness, which to some extent affects their dielectric stability and structural reliability during application. Summary of the Invention

[0004] The purpose of this application is to provide a silica and its preparation method, composite powder, resin composition and its application, wherein the silica achieves high porosity while also retaining its mechanical strength and toughness to the maximum extent.

[0005] For the purposes mentioned above, this application provides the following technical solution: In a first aspect, this application provides a silica comprising porous silica microspheres. In an SEM image of the porous silica microspheres, multiple dispersed first regions and second regions are included. The distance between two adjacent first regions is less than 2 μm. Each first region has a longest diameter, which is less than 2 μm. The multiple dispersed first regions have a total number of black pixels, and the porous silica microspheres have an overall total number of pixels. The ratio of the total number of black pixels to the overall total number of pixels is greater than 0.2.

[0006] Furthermore, in some embodiments, the ratio of the longest diameter of the first region to the diameter of the porous silica microsphere containing the first region is less than 1 / 3.

[0007] Furthermore, in some embodiments, the first region is circular, near-circular, or non-circular.

[0008] Furthermore, in some embodiments, the ratio of the distance between two adjacent first regions to the diameter of the porous silica microsphere containing the first region is less than 0.3 and greater than 0.01.

[0009] Furthermore, in some embodiments, the porous silica microspheres exhibit a multi-size distribution, wherein: the content of porous silica microspheres with a diameter <1μm is no more than 10%, the content of porous silica microspheres with a diameter of 1-10μm is 70%~95%, and the maximum diameter of the porous silica microspheres does not exceed 30μm.

[0010] Furthermore, in some embodiments, the first region is formed by the internal pores of the porous silica microspheres, and the second region is formed by the skeletal structure of the porous silica microspheres.

[0011] Furthermore, in some embodiments, the internal porosity of the porous silica microspheres is 40%-95%, preferably 60%-95%, and more preferably 70%-95%.

[0012] Furthermore, in some embodiments, the silicon dioxide satisfies one or more of the following conditions: (1) Dielectric constant < 3, preferably < 2; (2) Dielectric loss < 0.2%, preferably < 0.08%; (3) Surface hydroxyl content < 100 ppm; (4) Sphericity > 95%, preferably > 99%; (5) Specific surface area < 50m² 2 / g, preferably <15m 2 / g, more preferably <7m 2 / g; (6) Moisture content < 500 ppm / m 2 ; (7) Carbon content is less than 0.1%; (8) The breakage rate is <10%, preferably <5%.

[0013] Secondly, this application also provides a method for preparing silicon dioxide, comprising the following steps: S1: Prepare O / W prepolymer using raw materials containing a first silicon source and a polymer; S2. The O / W prepolymer prepared in S1 is used to form a W / O / W dispersion; S3. React the W / O / W dispersion prepared in S2 to obtain a silica dispersion; S4. React the silica dispersion prepared in step S3 with the second silicon source to obtain silica.

[0014] Furthermore, in some embodiments, the raw materials include a first silicon source, a hydrophilic polymer, a first solvent, and water, in a mass ratio of 1:(0.01-0.2):(0.01-1):(0.01-0.2).

[0015] Furthermore, in some embodiments, S4 includes a calcination step, wherein the calcination includes: a first stage of calcination, with a calcination temperature of 350℃-700℃ and a calcination time of 2h-6h; and a second stage of calcination, with a calcination temperature of 800℃-1000℃ and a calcination time of 1h-6h.

[0016] Furthermore, in some embodiments, the raw material is mixed with an acidic catalyst for reaction, wherein the mass ratio of the acidic catalyst to the first silicon source is (0.001-0.2):1.

[0017] Furthermore, in some embodiments, the O / W prepolymer in S2 is mixed with the water to form a dispersion, and the mass ratio of the O / W prepolymer to the water is 1:(3-50).

[0018] Furthermore, in some embodiments, the dispersion is formed in S2 by high-speed shear emulsification, which includes: an emulsifier shear rate of 700-10000 rpm and emulsification for 1-60 min.

[0019] Furthermore, in some embodiments, the W / O / W dispersion prepared in S2 and the alkaline catalyst are mixed in S3, the pH of the W / O / W emulsion is adjusted to 7-12, and the molar concentration of the alkaline catalyst is 0.1-5M.

[0020] Furthermore, in some embodiments, the mass ratio of the second silicon source to the first silicon source in S4 is (0.01-0.3):1.

[0021] Thirdly, this application also provides a composite powder, which includes at least the aforementioned silicon dioxide and a first inorganic substance, wherein the first inorganic substance includes at least one of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, boron nitride, aluminum nitride, and silicon nitride.

[0022] Fourthly, this application also provides a resin composition comprising a resin, and further comprising the silica described above or the silica prepared by the above preparation method or the composite powder described above.

[0023] Fifthly, this application also provides applications of the above-mentioned silica, composite powder, and resin composition, including applications in electronic components or functional materials, wherein the electronic components are one of semiconductor devices, copper-clad laminates, integrated circuits, electronic chips, radio frequency devices, flexible display devices, antenna devices, flexible wiring devices, and sensor devices, and the functional materials are one of advanced packaging materials, thermal insulation materials, and lightweight materials.

[0024] The silica, its preparation method, composite powder, resin composition, and their applications provided in this application have the following excellent effects: This application controls the ratio of the first and second regions formed by porous silica microspheres, as well as the dimensional relationship between the diameter of the first region and the microsphere, the distance relationship between adjacent first regions, and the uniform distribution characteristics of the first region. This allows the microspheres to not only reliably, stably, and efficiently achieve a lower dielectric constant, but also to maintain sufficient strength and avoid problems such as collapse and pore breakage caused by excessively large pore sizes. The silica provided by this application achieves high porosity while maximizing the retention of the mechanical strength of the microspheres. In addition, by reinforcing the shell on the honeycomb pores through secondary coating, the silica has even higher strength and will not collapse.

[0025] The method for preparing silica provided in this application, through a high-speed shear emulsification step and a secondary coating step, enables the prepared silica to have a sufficiently high porosity and a more uniform pore distribution. In addition, the shell structure on the surface of the microspheres also ensures a more stable silica framework structure, thereby maximizing the preservation of the mechanical strength of the microspheres while ensuring high porosity. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a SEM image of the silica prepared in Example 1 of this application; Figure 2 This is a schematic diagram illustrating the interpretation of the first and second regions in the silica of this application; Figure 3 Here is a SEM image of the silica prepared in Comparative Example 1 of this application; Figure 4 This is a SEM image of the silica prepared in Comparative Example 2 of this application. Detailed Implementation

[0028] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] In a first aspect, this application provides a silica comprising porous silica microspheres. In the SEM image of the porous silica microspheres, multiple dispersed first regions and second regions are included. The distance D between two adjacent first regions is less than 2 μm. Each first region has a longest diameter d, which is less than 2 μm. The multiple dispersed first regions have a total number of black pixels, and the porous silica microspheres have a total total number of pixels. The ratio of the total number of black pixels to the total number of pixels is greater than 0.2.

[0030] Preferably, the ratio of the total number of black pixels to the total number of pixels is greater than 0.2 and less than 0.8. Further, the ratio of the total number of black pixels to the total number of pixels can be 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8.

[0031] In this application, the silica comprises a plurality of porous silica microspheres, which have a honeycomb structure, and the honeycomb structure characteristics can be displayed by SEM images. Specifically, the SEM images show a plurality of dispersed first regions and second regions, which are uniformly distributed within the second regions. The plurality of dispersed first regions have a total number of black pixels, and the porous silica microspheres have a total total number of pixels. The ratio of the total number of black pixels to the total number of pixels is measured by the following method: Silica was characterized using field emission scanning electron microscopy. 100 photos were randomly taken at 5K magnification. After image preprocessing, thresholding, and binarization using ImageJ software, the total number of black pixels in the first region of the porous silica microspheres and the total number of pixels in the whole were counted, and then the ratio between the two was calculated.

[0032] Compared to the traditional method of characterizing the overall porosity of a product through porosity, SEM images can more clearly characterize the honeycomb-like structural features, especially the uniform distribution of pores.

[0033] When the proportion of the first region in the porous silica microspheres is greater than 0.2, the silica exhibits a microstructure with high porosity, which can meet the requirement of low dielectric constant.

[0034] The distance D between two adjacent first regions is less than 2 μm, where D is the minimum distance between the edges of two adjacent first regions. Further, the distance D does not exceed 1 μm and can be values ​​such as 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1. When D is less than 2 μm, the skeletal portion of the silica microsphere has a relatively small distance, resulting in a relatively dense first region of the silica microsphere. Therefore, compared to the non-uniform distribution of pores within some silica particles, the pores in the silica microspheres described in this application are uniformly distributed on the microsphere, with the distance between adjacent pores maintained within a certain range. This ensures a uniform electric field on the dielectric layer, maintains stable overall dielectric properties, and avoids the formation of localized high-dielectric regions that could lead to breakdown, reducing product reliability and lifespan. Furthermore, the uniformly distributed pores not only allow stress to be evenly distributed throughout the material network but also maximize the preservation of the material's mechanical strength and toughness while achieving high porosity. Most of these pores are nanoscale pores, with the longest diameter d in the first region being less than 2 μm. In addition to achieving a lower dielectric constant (such as further reducing the overall polarization of the material through the size effect of the pores), this also helps to maintain sufficient strength and avoid problems such as collapse and pore breakage caused by excessively large pore sizes.

[0035] Specifically, the longest diameter d of the first region can be 1.8, 1.6, 1.5, 1.3, 1.2, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, etc.

[0036] The ratio of the longest diameter d of the first region to the diameter of the porous silica microsphere containing the first region is less than 1 / 3. A reasonable pore size and uniform pore distribution determine whether the material can reliably, stably, and efficiently achieve a low dielectric constant and meet other stringent industrial requirements.

[0037] The first region is circular, near-circular, or non-circular, and may be elliptical. The first region has a longest diameter, defined as the maximum straight-line distance between two points on the region's boundary. When the first region is circular, this longest diameter is the diameter of the circle.

[0038] In some embodiments, the ratio of the distance D between two adjacent first regions to the diameter of the porous silica microsphere containing the first region is less than 0.3 and greater than 0.01. A small distance between two adjacent first regions reflects uniform distribution, ensuring a uniform electric field across the dielectric layer, maintaining stable overall dielectric properties, and preventing the formation of localized high-dielectric regions that could lead to breakdown and reduce product reliability and lifespan.

[0039] In some embodiments, the first region is formed by the internal pores of the porous silica microspheres, and the second region is formed by the skeletal structure of the porous silica microspheres.

[0040] Furthermore, the plurality of first regions are evenly distributed in the second region.

[0041] The porous silica microspheres are filled with air, which achieves the purpose of reducing the dielectric constant of silica.

[0042] In some embodiments, the porous silica microspheres exhibit a multi-size distribution, wherein: the content of porous silica microspheres with a diameter <1μm is no more than 10%, the content of porous silica microspheres with a diameter of 1-10μm is 70%~95%, and the maximum diameter of the porous silica microspheres does not exceed 30μm.

[0043] In this application, when silica is added to resin to prepare copper-clad laminate, particles of 1-10 μm serve as the main particles, while fine powder smaller than 1 μm fills the pores between the main particles, forming a highly dense and homogeneous composite structure. This structure can produce an effect similar to a ball bearing effect, improving fluidity, reducing viscosity, and increasing the filling amount. Furthermore, controlling the fine powder content to within 10% avoids a sharp increase in interface area due to excessive fine powder content, which could lead to increased losses. Controlling the maximum particle size to within 30 μm ensures the flatness of the board surface and avoids affecting signal transmission (especially the skin effect at high frequencies).

[0044] In some embodiments, the internal porosity of the silica is 40%-95%, preferably 60%-95%, and more preferably 70%-95%. When the internal porosity of the silica is controlled at 70%-95%, the mechanical strength and toughness of the microspheres can still be maximized.

[0045] In some embodiments, the surface hydroxyl content of the silica is <100 ppm; In some embodiments, the dielectric constant of the silicon dioxide is <3, preferably <2.

[0046] In some embodiments, the dielectric loss of the silicon dioxide is <0.2%, preferably <0.08%.

[0047] In the field of semiconductor packaging materials such as high-frequency and high-speed copper-clad laminates, surface hydroxyl content, dielectric constant, and low dielectric loss are core requirements. Low surface hydroxyl content can reduce dielectric loss, while low dielectric constant and low dielectric loss can improve the performance of high-frequency circuits and reduce signal transmission delay and energy loss. Therefore, the lower the dielectric constant and dielectric loss, the better.

[0048] In some embodiments, the sphericity of the silica is >95%, preferably >99%; in some embodiments, the specific surface area of ​​the silica is <50 m². 2 / g, preferably with a specific surface area <15m² 2 / g, more preferably a specific surface area <7m² 2 Microspheres with high specific surface areas tend to have numerous dangling bonds or adsorbed water molecules on their surface, increasing dielectric loss. Furthermore, a high specific surface area implies more surfaces and interfaces (such as grain boundaries, phase boundaries, and porous surfaces). Under an alternating electric field, free charges (electrons and ions) accumulate at these interfaces, creating additional polarization and significantly increasing the dielectric constant. Therefore, the specific surface area should not be too high.

[0049] In some embodiments, the water content of the silica is <500 ppm / m 2 Excessive moisture content significantly increases the electrical conductivity loss of the material, leading to a dramatic increase in dielectric loss. Furthermore, it makes downstream applications more susceptible to environmental influences and reduces stability. Therefore, the moisture content of silica should be <500ppm / m³. 2 .

[0050] In some embodiments, the carbon content of the silicon dioxide is <0.1%. In this application, an excessively high carbon content would increase the dielectric loss of the silicon dioxide.

[0051] In some embodiments, the porosity of the silica is <10%, preferably <5%.

[0052] In this application, the porosity refers to the proportion of silica particles with internally broken pores, where the broken pores no longer exist inside the particles. An excessively high porosity will lead to an increase in the specific surface area of ​​the microspheres, a deterioration in dielectric properties, and also cause the microspheres to collapse easily, resulting in an unstable silica framework and a decrease in the mechanical strength of the microspheres.

[0053] Secondly, this application also provides a method for preparing silicon dioxide, comprising the following steps: S1: Prepare O / W prepolymer using raw materials containing a first silicon source and a polymer; S2. The O / W prepolymer prepared in S1 is used to form a W / O / W dispersion; S3. React the W / O / W dispersion prepared in S2 to obtain a silica dispersion; S4. React the silica dispersion prepared in step S3 with the second silicon source to obtain honeycomb porous silica.

[0054] In some embodiments, the raw materials in S1 include a first silicon source, a hydrophilic polymer, a first solvent, and water, in a mass ratio of 1:(0.01-0.2):(0.01-1):(0.01-0.2).

[0055] In some embodiments, the mass ratio of the acidic catalyst to the first silicon source in S1 is (0.001-0.2):1.

[0056] In some embodiments, in step S1, the reaction temperature is 60-180°C and the reaction time is 0.1h-24h.

[0057] In some embodiments, in step S1, the raw material is mixed with an acidic catalyst and reacted, wherein the mass ratio of the acidic catalyst to the first silicon source is (0.001-0.2):1.

[0058] In some embodiments, in S1, the first silicon source is selected from tetraalkoxysiloxane, organosiloxane, or polyalkoxysiloxane with a silica content of less than 60%.

[0059] In some embodiments, in S1, the hydrophilic polymer is selected from at least one of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polysorbate, polyethylene glycol monomethyl ether, and polyether-modified silicone oil.

[0060] In some embodiments, in S1, the first solvent is selected from at least one of ethanol, methanol, isopropanol, ethylene glycol, propylene glycol, acetone, butanone, n-butanol, cyclohexane, etc.

[0061] In some embodiments, in step S2, the O / W prepolymer is mixed with water to form a dispersion, and the mass ratio of the O / W prepolymer to the water is 1:(3-50).

[0062] In some embodiments, in S2, a dispersion is formed by high-speed shear emulsification, which is an emulsification process performed using equipment with emulsification function, including but not limited to homogenizers and emulsifiers.

[0063] In some embodiments, in S2, the high-speed shear emulsification process is performed using an emulsifier, wherein the shear rate of the emulsifier is 700-10000 rpm and the emulsification time is 1-60 min.

[0064] In some embodiments, in S2, the high-speed shear emulsification process is performed by using a homogenizer to cycle 1-10 times at a pressure of 50-1000 bar.

[0065] In this application, S1 forms an O / W prepolymer, which consists of an oil phase and an internal aqueous phase. The oil phase forms a silica framework in subsequent steps, while the internal aqueous phase forms corresponding internal pores in subsequent steps.

[0066] In this application, S2 forms a W / O / W dispersion, corresponding to the external aqueous phase, oil phase, and internal aqueous phase, respectively. High-speed shear emulsification in S2 generates stronger shear forces, impact forces, and cavitation effects, allowing the external aqueous phase to better penetrate the prepolymer oil phase, forming a honeycomb structure and ensuring sufficient porosity. Secondly, high-speed shearing results in more uniform emulsification, narrower microsphere size distribution, more controllable honeycomb pore size, and, more importantly, a more uniform distribution of honeycomb pores on the microspheres.

[0067] If the shear rate is too low, the droplets will not break up sufficiently and the oil film will be stretched too little, resulting in larger W / O / W droplets and a relatively thick skeleton. This leads to an increase in the number of microspheres larger than 30 μm, excessively large microsphere size, decreased encapsulation efficiency, reduced porosity, and increased dielectric constant.

[0068] If the shear rate is too high, smaller droplets and thinner shells will be generated, posing a risk of excessive damage leading to leakage of the internal aqueous phase. This increases the number of microspheres smaller than 1 μm, resulting in a larger specific surface area and poorer processing performance. Furthermore, the thinner shells are more prone to causing the honeycomb pores of the microspheres to collapse and break, creating openings and increasing dielectric loss.

[0069] In some embodiments, in step S3, the W / O / W dispersion prepared in step S2 is reacted with an alkaline catalyst to prepare a silica dispersion. The alkaline catalyst is added to adjust the pH of the W / O / W emulsion to 7-12, and the molar concentration of the alkaline catalyst is 0.1-5M.

[0070] In some embodiments, in step S3, the reaction temperature is 0-80°C and the reaction time is 4-120 hours.

[0071] In some embodiments, in step S3, the alkaline catalyst is selected from at least one of sodium hydroxide, ammonia, potassium hydroxide, dodecylamine, and isopropylamine.

[0072] In some embodiments, the mass ratio of the second silicon source to the first silicon source in step S4 is (0.01-0.3):1.

[0073] In this application, an excessive amount of the second silicon source will result in it not being able to completely coat the silica microsphere shell, thus forming a large number of free small particles or fuzz.

[0074] In some embodiments, the second silicon source in S4 is selected from at least one of tetraalkoxysiloxane, organosiloxane, or polyalkoxysiloxane with a silica content of less than 60%.

[0075] In some embodiments, the reaction in S4 is a secondary coating reaction, the reaction temperature is 30-120°C, and the reaction time is 4-120 hours.

[0076] The secondary coating reaction involves introducing a second silicon source onto the surface of the silica prepared in S3 to form a coating layer. That is, the porous silica microspheres have a coating layer on their surface, thereby reinforcing the shell on the honeycomb pores, giving it higher strength and preventing it from collapsing.

[0077] The amount of silicon source in the secondary coating process needs to be controlled. Too much silicon source will result in the inability to completely coat the silica shell, forming a large number of free small particles or fuzz balls; while too little silicon source will fail to achieve the purpose of reinforcement, resulting in an excessively high porosity. Therefore, controlling the mass ratio of the second silicon source to the O / W prepolymer within the range of (0.01-0.3):1 can better reinforce the shell layer on the surface of the microspheres, thereby maximizing the mechanical properties of the microspheres.

[0078] In some embodiments, S4 includes a calcination step, wherein the calcination includes: a first stage of calcination at a temperature of 350℃-700℃ for a time of 2h-6h; and a second stage of calcination at a temperature of 800℃-1100℃ for a time of 1h-6h.

[0079] In some embodiments, before the first stage of calcination in S4, the heating rate is 0.1℃ / min-5℃ / min; after the first stage of calcination and before the second stage of calcination, the heating rate is 1℃ / min-10℃ / min.

[0080] Thirdly, this application also provides a composite powder, which includes at least the aforementioned silicon dioxide and a first inorganic substance, wherein the first inorganic substance includes at least one of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, boron nitride, aluminum nitride, and silicon nitride.

[0081] Fourthly, this application also provides a resin composition comprising a resin and further comprising the aforementioned silica or the aforementioned composite powder.

[0082] Fifthly, this application also provides an application of the above-mentioned silica, composite powder, and resin composition, wherein the silica, composite powder, or resin composition is used in electronic components or functional materials, wherein the electronic components are one of semiconductor devices, copper-clad laminates, integrated circuits, electronic chips, radio frequency devices, flexible display devices, antenna devices, flexible wiring devices, and sensor devices, and the functional materials are one of advanced packaging materials, thermal insulation materials, and lightweight materials.

[0083] In order to enable those skilled in the art to clearly understand the above-described implementation details and operations of this application, and to demonstrate the significant improvement in the performance of the electrolyte provided by the embodiments of this application, the above technical solutions are illustrated below through examples.

[0084] 1. Pixel Ratio Test Method In silicon dioxide, the ratio of the total number of black pixels to the total number of pixels is measured by the following method: Silica was characterized using field emission scanning electron microscopy. One hundred random photographs were taken at 5Kx magnification. Image preprocessing was performed using ImageJ software to enhance contrast, widening the grayscale difference between the holes and the silica framework. Noise filtering was then applied to remove image noise and prevent misidentification of noise as holes. Finally, the images were binarized: an algorithm selected an appropriate grayscale threshold to convert the grayscale image into a binary image containing only black and white.

[0085] The total number of black pixels in the first region of the porous silica microspheres and the total number of pixels in the whole are counted, and then the ratio between the two is calculated.

[0086] 2. Test method for pore breakage rate Characterization was performed using field emission scanning electron microscopy. At least 5-10 images from different fields of view were acquired, and 10 photos were randomly taken at 2K magnification. Microspheres with broken shells, obvious holes (especially at the top or sides), severe collapse, or shells missing more than half were identified as perforated microspheres.

[0087] Pore ​​rate = number of broken microspheres / total number of microspheres.

[0088] 3. Internal porosity testing method The silica was placed in a vacuum oven and treated at 110°C for 4 hours, and then the porosity was tested using the mercury intrusion porosimetry method.

[0089] Total porosity = Measured total pore volume / Total volume of the sample including all pores.

[0090] 4. Moisture content testing method Silica was placed at 25°C and 50%RH for 24 hours, and then the water content was tested using Karl Fischer titration.

[0091] 5. Microsphere size testing method Using a scanning electron microscope, 100 photos were randomly taken at 2Kx magnification. The electron microscope images were imported into the image analysis software ImageJ, and the pixels were converted into actual sizes through "calibration". Then the microspheres were measured and statistically analyzed.

[0092] Select the microsphere with the largest particle size from the electron microscope image. For this microsphere, mark and record the maximum value of the longest diameter d of the first region, dmax, and the maximum value of the distance D between two adjacent first regions, Dmax.

[0093] 6. Relative permittivity test method The test was conducted using a vector network analyzer and a cylindrical resonant cavity.

[0094] First, mix silica powder and paraffin wax at a weight ratio of 44:56 until homogeneous. This process can be repeated 3-5 times by alternating between melting, grinding, and cooling to ensure uniform mixing.

[0095] 1.61 g of the powder after the final cooling was pressed into a disc with a diameter of 15.1 ± 0.1 mm and a height of 7.75 ± 0.03 mm. The disc was placed in the center of the resonant cavity for testing at a frequency of 13 GHz. The relative permittivity Dk of the silica powder + paraffin mixture was obtained. 混 Given that the relative permittivity of paraffin is 3.8, calculate the relative permittivity of silica powder.

[0096] Dk 二氧化硅 =(Dk 混 -3.8×56%) / (44%).

[0097] 7. Dielectric Loss Test Method The test was conducted using a vector network analyzer and a cylindrical resonant cavity.

[0098] First, mix silica powder and paraffin wax at a weight ratio of 44:56 until homogeneous. This process can be repeated 3-5 times by alternating between melting, grinding, and cooling to ensure uniform mixing.

[0099] 1.61 g of the powder after the final cooling was pressed into a disc with a diameter of 15.1 ± 0.1 mm and a height of 7.75 ± 0.03 mm. The disc was placed in the center of the resonant cavity for testing at a frequency of 13 GHz. The dielectric loss Df of the silica powder + paraffin mixture was obtained. 混 .

[0100] Because paraffin has relatively low dielectric loss, it is generally considered that Df 二氧化硅 =Df 混 This leads to the dielectric loss of silicon dioxide.

[0101] 8. Sphericity Test Method Characterization was performed using field emission scanning electron microscopy. Five images were randomly taken at 10,000x magnification. One hundred particles were selected, and the sphericity was calculated using the image processing software ImageJ.

[0102] Sphericity = 4π × area / perimeter 2 .

[0103] 9. Specific surface area testing method The surface area was measured using a micromeritics surface area analyzer.

[0104] 10. Methods for testing moisture content Silica was placed at 25°C and 50%RH for 24 hours, and then the water content was tested using Karl Fischer titration.

[0105] 11. Carbon content testing method The tests were conducted using a carbon, sulfur, oxygen, and nitrogen analyzer.

[0106] Example 1 Preparation of silicon dioxide: S1. Preparation of O / W type emulsion: Disperse 95g tetraethyl silicate, 8g polyethylene glycol, 5g ethanol, and 5g water evenly under stirring at 300rpm to form a transparent solution. Add 4g (H + An O / W prepolymer was obtained by heating a 2M hydrochloric acid solution at 120°C for 2 hours.

[0107] S2. Preparation of W / O / W type multiple emulsion: The W / O prepolymer obtained in step S1 is added to water (O / W prepolymer: water mass ratio 1:5), and emulsified for 10 min under high-speed shear emulsification at 3k rpm in an emulsifier to form a stable W / O / W dispersion.

[0108] S3. Preparation of silica dispersion: Add 2M sodium hydroxide solution to the W / O / W dispersion to make the pH reach 11, and continue to react at 17°C for 48 hours to obtain silica dispersion.

[0109] S4. Add 7g of methyltrimethoxysilane to the silica dispersion obtained in step S3. After stirring continuously at 60℃ for 48h, wash, dry, and then perform gradient calcination: the dried product is first heated to 500℃ at 0.3℃ / min and held for 3h, then heated to 950℃ at 5℃ / min and held for 4h to obtain silica.

[0110] Example 2 Preparation of silicon dioxide: S1. Preparation of O / W type emulsion: Disperse 95g tetraethyl silicate, 8g polyvinyl alcohol, 10g methanol, and 4g water evenly under stirring at 300rpm to form a transparent solution. Add 8g (H... + An O / W prepolymer was obtained by heating a 1M hydrochloric acid solution at 120°C for 2 hours. S2. Preparation of W / O / W type multiple emulsion: The W / O prepolymer obtained in step S1 is added to water (O / W prepolymer: water mass ratio 1:5), and emulsified for 10 min under high-speed shear emulsification at 5k rpm in an emulsifier to form a stable W / O / W dispersion.

[0111] S3. Preparation of silica dispersion: Add 2M ammonia solution to the W / O / W dispersion to make the pH reach 11, and continue to react at 17°C for 48 hours to obtain silica dispersion.

[0112] S4. Add 7g of tetraethyl silicate to the silica dispersion obtained in step S3. After stirring continuously at 60℃ for 48h, wash, dry, and then perform gradient calcination: the dried product is first heated to 500℃ at 0.3℃ / min and held for 3h, then heated to 950℃ at 5℃ / min and held for 4h to obtain silica.

[0113] Example 3 Preparation of silicon dioxide: S1. Preparation of O / W type emulsion: Disperse 95g methyltrimethoxysilane, 8g polyethylene glycol monomethyl ether, 20g isopropanol, and 4g water evenly under stirring at 300rpm to form a transparent solution. Add 10g (H... + An acetic acid solution with a concentration of 1M was heated at 120°C for 2 hours to obtain an O / W prepolymer. S2. Preparation of W / O / W type multiple emulsion: The W / O prepolymer obtained in step S1 is added to water (O / W prepolymer: water mass ratio 1:10), and emulsified for 10 min under high-speed shear emulsification at 7k rpm in an emulsifier to form a stable W / O / W dispersion.

[0114] S3. Preparation of silica dispersion: Add 2M dodecylamine solution to the W / O / W dispersion to make the pH reach 11, and continue to react at 17°C for 48 hours to obtain silica dispersion.

[0115] S4. Add 9.5g of methyltrimethoxysilane to the silica dispersion obtained in step S3. After stirring continuously at 60℃ for 48h, wash, dry, and then perform gradient calcination: the dried product is first heated to 500℃ at 0.3℃ / min and held for 3h, then heated to 950℃ at 5℃ / min and held for 4h to obtain silica.

[0116] Example 4 Preparation of silicon dioxide: S1. Preparation of O / W type emulsion: 95g tetramethoxysilane, 16g polyethylene glycol, 10g ethylene glycol, and 5g water are dispersed evenly under stirring at 300rpm to form a transparent solution. 6g (H...) + An oxalic acid solution with a concentration of 1M was heated at 120°C for 2 hours to obtain an O / W prepolymer. S2. Preparation of W / O / W type multiple emulsion: The W / O prepolymer obtained in step S1 is added to water (O / W prepolymer: water mass ratio 1:20), and emulsified for 5 min under high-speed shear emulsification at 8k rpm in an emulsifier to form a stable W / O / W dispersion.

[0117] S3. Preparation of silica dispersion: Add 2M ammonia solution to the W / O / W dispersion to make the pH reach 11, and continue to react at 17°C for 48 hours to obtain silica dispersion.

[0118] S4. Add 4.75g of methyltrimethoxysilane to the silica dispersion obtained in step S3. After stirring continuously at 80℃ for 24h, wash, dry, and then perform gradient calcination: the dried product is first heated to 500℃ at 0.3℃ / min and held for 3h, then heated to 950℃ at 5℃ / min and held for 4h to obtain silica.

[0119] Example 5 Preparation of silicon dioxide: S1. Preparation of O / W type emulsion: Disperse 95g tetraethyl silicate, 16g polyethylene glycol, 10g ethylene glycol, and 9g water evenly under stirring at 300rpm to form a transparent solution. Add 3g (H + An O / W prepolymer was obtained by heating a 2M hydrochloric acid solution at 120°C for 2 hours. S2. Preparation of W / O / W type multiple emulsion: The W / O prepolymer obtained in step S1 is added to water (O / W prepolymer: water mass ratio 1:30), and emulsified for 5 min under high-speed shear emulsification at 8k rpm in an emulsifier to form a stable W / O / W dispersion.

[0120] S3. Preparation of silica dispersion: Add 2M ammonia solution to the W / O / W dispersion to make the pH reach 11, and continue to react at 17°C for 48 hours to obtain silica dispersion.

[0121] S4. Add 16.15g of methyltrimethoxysilane to the silica dispersion obtained in step S3. After stirring continuously at 40℃ for 72h, wash, dry, and then perform gradient calcination: the dried product is first heated to 500℃ at 0.3℃ / min and held for 3h, then heated to 950℃ at 5℃ / min and held for 4h to obtain silica.

[0122] Example 6 Preparation of silicon dioxide: S1. Preparation of O / W type emulsion: Disperse 95g tetraethyl silicate, 16g polyethylene glycol, 10g ethylene glycol, and 10g water evenly under stirring at 300rpm to form a transparent solution. Add 2g (H+ An O / W prepolymer was obtained by heating a 2M hydrochloric acid solution at 120°C for 2 hours. S2. Preparation of W / O / W type multiple emulsion: The W / O prepolymer obtained in step S1 is added to water (O / W prepolymer: water mass ratio is 1:10), and emulsified for 3 minutes under high-speed shear emulsification at 10k rpm in an emulsifier to form a stable W / O / W dispersion.

[0123] S3. Preparation of silica dispersion: Add 2M ammonia solution to the W / O / W dispersion to make the pH reach 11, and continue to react at 17°C for 48 hours to obtain silica dispersion.

[0124] S4. Add 19g of methyltrimethoxysilane to the silica dispersion obtained in step S3. After stirring continuously at 60℃ for 24h, wash, dry, and then perform gradient calcination: the dried product is first heated to 500℃ at 0.3℃ / min and held for 3h, then heated to 950℃ at 5℃ / min and held for 4h to obtain silica.

[0125] Comparative Example 1 Preparation of silicon dioxide: S1. Preparation of O / W type emulsion: Disperse 95g tetraethyl silicate, 16g polyethylene glycol, 10g ethanol, and 10g water evenly under stirring at 300rpm to form a transparent solution. Add 2g (H + An O / W prepolymer was obtained by heating a 2M hydrochloric acid solution at 120°C for 2 hours.

[0126] S2. Preparation of W / O / W type multiple emulsion: The W / O prepolymer obtained in step S1 is added to water (O / W prepolymer: water mass ratio 1:10), and emulsified for 3 minutes under high-speed shear emulsification at 10k rpm in an emulsifier to form a stable W / O / W dispersion.

[0127] S3. Preparation of silica dispersion: Add 2M sodium hydroxide solution to the W / O / W dispersion to make the pH reach 11, and continue to react at 17°C for 48 hours to obtain silica dispersion.

[0128] S4. The silica dispersion obtained in step S3 is washed, dried, and subjected to gradient calcination: the dried product is first heated to 500 ℃ at 0.3 ℃ / min and held for 3 h, then heated to 950 ℃ at 5 ℃ / min and held for 4 h to obtain silica.

[0129] Comparative Example 2 Preparation of silicon dioxide: S1. Preparation of O / W type emulsion: Disperse 95g tetraethyl silicate, 4.75g polyethylene glycol, 5g ethanol, and 5g water evenly under stirring at 300rpm to form a transparent solution. Add 4g (H + An O / W prepolymer was obtained by heating a 2M hydrochloric acid solution at 120°C for 2 hours. S2. Preparation of W / O / W type multiple emulsion: Add the W / O prepolymer obtained in step S1 into water (O / W prepolymer: water mass ratio 1:5), and emulsify for 10 min under conventional stirring at 200 rpm in an emulsifier to form a stable W / O / W dispersion.

[0130] S3. Preparation of silica dispersion: Add 2M sodium hydroxide solution to the W / O / W dispersion to make the pH reach 11, and continue to react at 17°C for 48 hours to obtain silica dispersion.

[0131] S4. Add 7g of methyltrimethoxysilane to the silica dispersion obtained in step S3. After stirring continuously at 60℃ for 48h, wash, dry, and then perform gradient calcination: the dried product is first heated to 500℃ at 0.3℃ / min and held for 3h, then heated to 950℃ at 5℃ / min and held for 4h to obtain silica.

[0132] Comparative Example 3 The silica prepared in Example 4 disclosed in CN118579799A was used as a comparative example.

[0133] Scanning electron microscopy (SEM) analysis was performed on the silica prepared in Examples 1-6 and Comparative Examples 1-3. The pixel ratio, the maximum value of the longest diameter d of the first region (dmax), and the maximum value of the distance D between two adjacent first regions (Dmax) were statistically analyzed. Porosity, porosity, particle size distribution, dielectric constant, dielectric loss, sphericity, specific surface area, water content, and carbon content were also measured, and the results are shown in Table 1. Figures 1-4 The data shown.

[0134] Table 1 Performance Parameters

[0135] As can be seen from the table above: (1) As can be seen from the pixel ratio, dmax, and Dmax values ​​of the silicon dioxide described in Examples 1-6, the pores in the silicon dioxide described in this application are uniformly distributed on the microspheres, and the distance between adjacent pores is maintained within a certain range, so that the electric field borne by the dielectric layer is uniform, the overall dielectric properties remain stable, and the generation of local high dielectric regions is avoided, which would lead to breakdown and reduce the reliability and lifespan of the product. In addition, the uniformly distributed pores and the appropriate pore size can not only make the stress uniformly distributed throughout the material network, but also maximize the preservation of the mechanical strength and toughness of the material while achieving high porosity.

[0136] (2) The mass ratio of the second silicon source to the first silicon source is (0.01-0.3):1. The secondary coating shell is more stable, which can ensure the mechanical properties of the microspheres and give the silicon dioxide higher strength, preventing it from collapsing. If the secondary coating is not performed (Comparative Example 1), the strength of the microspheres decreases, the porosity increases sharply, and the specific surface area increases.

[0137] (3) High-speed shear emulsification treatment results in silica with sufficiently high porosity and more uniform pore distribution, and a lower pore breakage rate. If the shear rate of high-speed shear emulsification is too low (Comparative Example 2), it will lead to insufficient droplet breakage and low oil film stretching, resulting in larger W / O / W droplets and a relatively thick skeleton, thus reducing porosity and causing uneven pore distribution, such as... Figure 4 As shown, because the generated pores are not obvious, the spherical silicon appears solid overall, so the pore size and interpore spacing cannot be measured. The number of microspheres larger than 30 μm increases, resulting in excessively large microsphere size, decreased coating efficiency, reduced porosity, and increased dielectric constant.

[0138] (4) The silica microspheres described in this application have a honeycomb porous structure inside, while the silica prepared in Comparative Example 3 (Example 4 of CN118579799A) has a hollow spherical structure. Specifically, the spherical silica has a central macropore and a shell, with the shell having a honeycomb porous structure. Due to the presence of the central macropore, the mechanical strength of the spherical silica is poor. The silica prepared in this application achieves similar properties to hollow spherical silica. At the same time, because there is no central macropore, the original central macropore becomes an internal framework. Due to the prevalence of the framework in honeycomb spherical silica, it supports the honeycomb spherical silica, effectively improving its mechanical strength. In addition, the D of Comparative Example 3 max The diameter is 3μm. It can be seen that the skeleton in its shell is relatively large and the honeycomb pores are unevenly distributed. However, the honeycomb pore distribution of the silicon dioxide described in this application is more reasonable and uniform than that of the honeycomb shell of hollow spherical silicon, thus further improving the supporting performance of the skeleton.

[0139] It is evident that by employing high-speed shear emulsification and secondary coating steps, while ensuring high porosity and more uniform pore distribution, the shell structure on the surface of the microspheres also ensures a more stable silica framework structure that will not collapse. Furthermore, it also exhibits lower dielectric constant and dielectric loss.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A type of silicon dioxide, characterized in that, Including porous silica microspheres; The SEM image of the porous silica microspheres includes multiple dispersed first regions and second regions. The multiple first regions are formed by the internal pores of the porous silica microspheres, and the second regions are formed by the framework of the porous silica microspheres. The distance between two adjacent first regions does not exceed 1 μm, and the first region has a longest diameter, which is less than 2 μm; The carbon content of the silicon dioxide is ≤0.05%; The plurality of first regions have a total number of black pixels, and the porous silica microspheres have a total total number of pixels. The ratio of the total number of black pixels to the total number of pixels is greater than 0.

2. The ratio of the total number of black pixels to the total number of pixels was measured using the following method: Silica was characterized using a field emission scanning electron microscope, and 100 photos were randomly taken at 5Kx magnification. Image preprocessing was performed using ImageJ software to enhance contrast and increase the grayscale difference between the holes and the silica skeleton. Then, noise filtering was performed to remove image noise and avoid misidentifying noise as holes. Finally, the image was binarized, specifically by selecting an appropriate grayscale threshold and converting the grayscale image into a binary image with only black and white colors. The total number of black pixels in the first region of the porous silica microspheres and the total number of pixels were counted, and then the ratio between the two was calculated.

2. The silicon dioxide according to claim 1, characterized in that, The ratio of the longest diameter of the first region to the diameter of the porous silica microsphere in which the first region is located is less than 1 / 3.

3. The silicon dioxide according to claim 1 or 2, characterized in that, The first region is circular, near-circular, or non-circular.

4. The silicon dioxide according to claim 1, characterized in that, The ratio of the distance between two adjacent first regions to the diameter of the porous silica microsphere containing the first region is less than 0.3 and greater than 0.

01.

5. The silicon dioxide according to claim 1, characterized in that, The porous silica microspheres exhibit a multi-size distribution, wherein: the content of porous silica microspheres with a diameter <1μm is no more than 10%, the content of porous silica microspheres with a diameter of 1-10μm is 70%~95%, and the maximum diameter of the porous silica microspheres does not exceed 30μm.

6. The silicon dioxide according to claim 1, characterized in that, The internal porosity of the porous silica microspheres is 40%-95%.

7. The silicon dioxide according to claim 1, characterized in that, The silicon dioxide satisfies one or more of the following conditions: (1) Dielectric constant < 3; (2) Dielectric loss < 0.2%; (3) Surface hydroxyl content < 100 ppm; (4) Sphericity > 95%; (5) Specific surface area < 50m² 2 / g; (6) Moisture content < 500 ppm / m 2 ; (7) The breakage rate is less than 10%.

8. A method for preparing silicon dioxide according to any one of claims 1-7, characterized in that, Includes the following steps: S1: After mixing the first silicon source, hydrophilic polymer, first solvent and water, an acidic catalyst is added to prepare an O / W prepolymer; S2. The O / W prepolymer prepared in S1 is subjected to high-speed shear emulsification to form a W / O / W dispersion. The high-speed shear emulsification includes: emulsifier shear rate of 700-10000 rpm, emulsification for 1-60 min. S3. React the W / O / W dispersion prepared in S2 to obtain a silica dispersion; S4. React the silica dispersion prepared in step S3 with the second silicon source to obtain silica.

9. The method for preparing silicon dioxide according to claim 8, characterized in that, The mass ratio of the first silicon source, the hydrophilic polymer, the first solvent, and water is 1:(0.01-0.2):(0.01-1):(0.01-0.2).

10. The method for preparing silicon dioxide according to claim 8, characterized in that, The S4 includes a calcination step, which includes: a first stage of calcination at a temperature of 350℃-700℃ for 2h-6h; and a second stage of calcination at a temperature of 800℃-1000℃ for 1h-6h.

11. The method for preparing silicon dioxide according to claim 8, characterized in that, The mass ratio of the acidic catalyst to the first silicon source is (0.001-0.2):1, and / or, In step S2, the O / W prepolymer is mixed with water to form a W / O / W dispersion, wherein the mass ratio of the O / W prepolymer to the water is 1:(3-50), and / or, In step S3, the W / O / W dispersion prepared in step S2 and the alkaline catalyst are mixed, the pH of the W / O / W dispersion is adjusted to 7-12, and the molar concentration of the alkaline catalyst is 0.1-5M, and / or... In step S4, the mass ratio of the second silicon source to the first silicon source is (0.01-0.3):

1.

12. A composite powder, characterized in that, The composite powder comprises at least the silicon dioxide according to any one of claims 1-7 or the silicon dioxide prepared by the preparation method according to any one of claims 8-11 and a first inorganic substance, wherein the first inorganic substance comprises at least one of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, boron nitride, aluminum nitride, and silicon nitride.

13. A resin composition, characterized in that, The resin composition includes a resin, and further includes silica according to any one of claims 1-7, or silica prepared by the preparation method according to any one of claims 8-11, or the composite powder according to claim 12.

14. The application of silica as described in any one of claims 1-7, silica prepared by the preparation method as described in any one of claims 8-11, the composite powder as described in claim 12, or the resin composition as described in claim 13, characterized in that, The applications include those for electronic components or functional materials, wherein the electronic components are one of semiconductor devices, copper-clad laminates, integrated circuits, electronic chips, radio frequency devices, flexible display devices, antenna devices, flexible wiring devices, and sensor devices, and the functional materials are one of advanced packaging materials, thermal insulation materials, and lightweight materials.

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