阅读说明：本技术 一种低介电常数中空氧化铝/二氧化硅纳米复合材料及应用 (Low-dielectric-constant hollow alumina/silicon dioxide nano composite material and application thereof ) 是由 宋锡滨 马雁冰 李心勇 潘光军 于 2020-06-04 设计创作，主要内容包括：本发明属于材料化学技术领域,具体涉及一种低介电常数中空氧化铝/二氧化硅纳米复合材料,并进一步公开其制备方法及应用。所述低介电常数中空氧化铝/二氧化硅纳米复合材料为具有闭合空腔结构的叠层壳体结构,通过在中空二氧化硅壳层外表面定向沉积氧化铝,其内层壳体为二氧化硅层,并在二氧化硅层表面沉淀生长氧化铝外壳壳体,有效结合了氧化铝与二氧化硅的优点,可同时发挥中空二氧化硅的低介电常数、低折射率、高频介电稳定性的优点,同时利用氧化铝材料高强度、抗化学侵蚀、热导率小、热膨胀系数低等优势,可适用于减反射领域及5G毫米波频段领域的性能要求。(The invention belongs to the technical field of material chemistry, and particularly relates to a low-dielectric-constant hollow alumina/silica nanocomposite, and further discloses a preparation method and application thereof. The low-dielectric-constant hollow alumina/silica nanocomposite is of a laminated shell structure with a closed cavity structure, alumina is directionally deposited on the outer surface of a hollow silica shell, an inner shell of the composite is a silica layer, and an alumina shell is deposited and grown on the surface of the silica layer, so that the advantages of the alumina and the silica are effectively combined, the advantages of the hollow silica such as low dielectric constant, low refractive index and high-frequency dielectric stability can be simultaneously exerted, and meanwhile, the low-dielectric-constant, low-refractive-index and high-frequency dielectric stability of the hollow silica can meet the performance requirements in the fields of antireflection and 5G millimeter wave frequency bands by utilizing the advantages of high strength, chemical erosion resistance, low thermal conductivity, low thermal expansion.)

1. A low dielectric constant hollow alumina/silica nanocomposite, comprising:

an inner cavity (1);

a silicon dioxide inner shell layer (2) which forms the inner cavity (2) in a coating manner; and the number of the first and second groups,

and the alumina outer shell layer (3) is coated on the outer surface of the silica inner shell layer (2).

2. The low dielectric constant hollow alumina/silica nanocomposite of claim 1, wherein the nanocomposite has the following dielectric properties:

the volume fraction of the cavity is more than 0-65%;

the dielectric constant in the flow direction of 20-43.5GHz band is 1.8-5.1, and the dielectric loss tangent is 0.0003-0.004;

young modulus is larger than 6GPa, and pencil hardness is tested between 5H and 7H.

3. A method for preparing the low dielectric constant hollow alumina/silica nanocomposite as claimed in claim 1 or 2, comprising the steps of:

(1) calcium chloride solution is taken as template solution, ammonia is added to adjust the pH value of the system to be alkaline, and then CO is continuously introduced₂Gas, forming nano calcium carbonate template particles;

(2) the obtained nano calcium carbonate template particles are calcined at the temperature of 100-800 ℃ after being separated, washed and dried; preparing calcined nano calcium carbonate template particles to form a dispersion liquid, and adding ammonia water to adjust the pH value to be alkaline; then adding an organic silicon solution for reaction; after the reaction is finished, removing impurity particles to obtain silicon dioxide particles with templates;

(3) dispersing the silica particles with the templates in a pure water solution, adding dilute acid to dissolve the templates, performing solid-liquid separation and washing, adding water to the obtained silica particles to prepare a dispersion solution, adding silica sol, mixing, and performing a curing reaction at 50-200 ℃; after the reaction is finished, separating, washing and drying to obtain hollow silicon dioxide particles;

(4) preparing the obtained hollow silica particles into dispersion liquid, and adding an ammonium bicarbonate solution for reaction; then adding a water-soluble aluminum salt solution, and adjusting the pH value of the system to be alkaline for reaction; after the reaction is finished, washing and drying to obtain nano hollow alumina/silicon dioxide powder;

(5) and calcining the obtained hollow alumina/silicon dioxide powder to obtain the hollow alumina/silicon dioxide powder.

4. The method for preparing a low dielectric constant hollow alumina/silica nanocomposite as claimed in claim 3, wherein in the step (1):

controlling the mass concentration of the calcium chloride solution to be 0.05-5 g/ml;

controlling the pH value of the ammonia water adjusting system to be 8-12;

the particle size of the nano calcium carbonate template particles is controlled to be 5-500 nm.

5. The method for preparing a low dielectric constant hollow alumina/silica nanocomposite as claimed in claim 3 or 4, wherein, in the step (2),

controlling the dispersion concentration of the template particles to be 0.03-0.8 g/ml;

controlling the pH value of the ammonia water adjusting system to be 9-13;

the organic silicon comprises silane and at least one of compounds of the silane and alcohols, halogenated silane, silicon ether and silicone.

6. The method for preparing a low dielectric constant hollow alumina/silica nanocomposite as claimed in any one of claims 3 to 5, wherein in the step (3):

controlling the dispersion concentration of the silica particles with the templates to be 0.05-1 g/ml;

controlling the dispersion concentration of the silicon dioxide particles to be 0.01-0.5 g/ml;

controlling the particle size of the silica sol to be 5-10nm and the content to be 10-30%;

the mass ratio of the silica sol to the silica particles is 0.001-0.1: 1.

7. the method for preparing a low dielectric constant hollow alumina/silica nanocomposite as claimed in any one of claims 3 to 6, wherein in the step (4):

controlling the dispersion concentration of the hollow silica particles to be 0.01-0.8 g/ml;

controlling the concentration of the ammonium bicarbonate solution to be 0.01-5 g/ml;

controlling the concentration of the water-soluble aluminum salt solution to be 0.01-5 g/ml;

the water-soluble aluminum salt comprises one or a mixture of two of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum ammonium sulfate and sodium metaaluminate and aluminum isopropoxide;

controlling ammonia water to adjust the pH value of the reaction system to 9-13.

8. The method as claimed in any one of claims 3 to 7, wherein the step (4) comprises a first calcination step at 300 ℃ and a second calcination step at 1000 ℃ and 100 ℃.

9. The method for preparing a low dielectric constant hollow alumina/silica nanocomposite as claimed in any one of claims 3 to 8, wherein:

in the step (1), a step of adding a surfactant into the calcium chloride solution is further included, wherein the mass ratio of the calcium chloride to the surfactant is controlled to be 5-40: 1;

in the step (2), a surfactant is added into the nano calcium carbonate template particle dispersion liquid, wherein the mass ratio of the nano calcium carbonate to the surfactant is controlled to be 5-20: 1.

10. use of the low dielectric constant hollow alumina/silica nanocomposite as claimed in claim 1 or 2 in the field of 5G communications.

Technical Field

The invention belongs to the technical field of material chemistry, and particularly relates to a low-dielectric-constant hollow alumina/silica nanocomposite, and further discloses a preparation method and application thereof.

Background

With the rapid development of science and technology, the IT era of high-speed development has been entered. In the field of information technology, which has been rapidly developed, various electronic products, systems, and devices are increasingly emerging. From industrial automation control systems to home-life electrical appliances, a large number of electronic circuits are involved. With the rapid growth of the electronic industry in the 21 st century, the influence on our lives and works is further deepened. The appearance of various sensors and electronic components plays a role of no substitution in various fields of national defense and national economy, and is widely applied in our lives. In the current IT and scientific and technical economy era, the electronic industry becomes an important economic growth point recognized by various countries and continuously promotes the vigorous development of global economy. With the advent of the 5G era, electronic technology has increasingly demanded materials, and not only has ever higher demands on the heat resistance, strength, corrosion resistance, insulation properties, and the like of dielectric materials, but also a more important demand has been to sufficiently reduce the dielectric constant of dielectric materials.

In the traditional circuit board material, the alumina ceramic has the advantages of high hardness, high wear resistance, high mechanical strength, high resistivity, good chemical stability, good dielectric property, good resistance to thermal shock, capability of forming sealed brazing with metal and the like, and the dielectric loss (tg) of the alumina ceramic is in a wider frequency range no matter the alumina ceramic is a polycrystalline material or a single crystal material, wherein the dielectric loss is still not large under the condition of ultrahigh frequency, the change of the alumina ceramic is not large along with the rise of temperature, the relation between the dielectric constant () and the temperature is not obvious, and the alumina ceramic is an ideal circuit board material and is widely used as a filling material for an upper cover plate, a heat-conducting ceramic substrate and a PCB (printed circuit board) of a chip packaging structural member. However, the dielectric constant of pure alumina can only reach 8 at the lowest, and the dielectric performance requirement under the high-frequency condition can not be met.

Porous SiO₂The material is a dielectric material which has received much attention in recent years, not only has a low dielectric constant, but also can be used in combination with the existing single crystal SiO₂The process is well compatible, is obviously superior to an organic medium in the aspects of thermal stability, adhesion to inorganic substances and the like, and is the traditional SiO₂The ideal substitute of (1). However, in the prior art, porous SiO is used₂The research on materials has mainly focused on how to reduce the dielectric constant of silicon oxide-based thin films, but relatively few studies have been made on how to effectively reduce the dielectric constant of silicon oxide materials themselves, and porous SiO materials have₂The dielectric properties of the material are greatly influenced by the preparation process, and the material is not beneficial to wide application.

Therefore, there is a strong need to develop a low dielectric constant material for high frequency applications to meet the performance requirements of high frequency devices.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to provide a hollow alumina/silicon dioxide nano composite material with a certain closed cavity structure, which can meet the requirements of the antireflection field, the 5G millimeter wave frequency band low dielectric constant and the high frequency dielectric stability;

the second technical problem to be solved by the invention is to provide a preparation method and application of the low-dielectric-constant hollow alumina/silica nanocomposite.

In order to solve the above technical problems, the present invention provides a low dielectric constant hollow alumina/silica nanocomposite, comprising:

an inner cavity;

a silicon dioxide inner shell layer which forms the inner cavity in a coating manner; and the number of the first and second groups,

and the alumina outer shell layer is coated on the outer surface of the silica inner shell layer.

2. The low dielectric constant hollow alumina/silica nanocomposite of claim 1, wherein the nanocomposite has the following dielectric properties:

the volume fraction of the cavity is more than 0-65%;

the dielectric constant in the flow direction of 20-43.5GHz band is 1.8-5.1, and the dielectric loss tangent is 0.0003-0.004;

young modulus is larger than 6GPa, and pencil hardness test is between 5H and 7H (the included angle between the pencil and the coating is 45 degrees, and the pencil is pushed at the speed of 1 mm/s). Specifically, the volume fraction of the cavity of the nano composite material can be controlled between 0% and 65%, the filling amount is between 1% and 80% when the nano composite material is used as a filling material or a coating material, and the coating or filling thickness can be varied from 20nm to 10um according to different coating or filling processes.

The shape of the inner cavity of the nano composite material depends on the shape of the inner layer hollow silicon dioxide template, and the reaction temperature and CaCl during template synthesis can be adjusted₂Concentration of solution, kind of solvent, CO₂Regulating the shape and size of the internal cavity by means of access and flow, addition of different crystal growth inhibitors, etc., e.g. using small bubbles and CO₂The mixed gas with higher content is beneficial to forming superfine calcium carbonate; square calcium carbonate is easy to obtain in a pure water system, and spherical calcium carbonate is easy to form in an ethanol system; a commonly used crystal form control agent is ZnCl₂、MgCl₂Or EDTA (ethylene diamine tetraacetic acid), disodium hydrogen phosphate, citric acid, H₂O₂Ethanolamine, sodium silicate, silk fibroin enzymolysis liquid, D-sodium gluconate, sodium carboxymethylcellulose and the like.

The invention also discloses a method for preparing the low-dielectric-constant hollow alumina/silicon dioxide nano composite material, which comprises the following steps:

(1) calcium chloride solution is taken as template solution, ammonia is added to adjust the pH value of the system to be alkaline, and then CO is continuously introduced₂Gas, forming nano calcium carbonate template particles;

(2) the obtained nano calcium carbonate template particles are calcined at the temperature of 100-800 ℃ after being separated, washed and dried; preparing calcined nano calcium carbonate template particles to form a dispersion liquid, and adding ammonia water to adjust the pH value to be alkaline; then adding an organic silicon solution for reaction; after the reaction is finished, removing impurity particles to obtain silicon dioxide particles with templates;

(3) dispersing the silica particles with the templates in a pure water solution, adding dilute acid to dissolve the templates, performing solid-liquid separation and washing, adding water to the obtained silica particles to prepare a dispersion solution, adding silica sol, mixing, and performing a curing reaction at 50-200 ℃; after the reaction is finished, separating, washing and drying to obtain hollow silicon dioxide particles;

(4) preparing the obtained hollow silica particles into dispersion liquid, and adding an ammonium bicarbonate solution for reaction; then adding a water-soluble aluminum salt solution, and adjusting the pH value of the system to be alkaline for reaction; after the reaction is finished, washing and drying to obtain nano hollow alumina/silicon dioxide powder;

(5) and calcining the obtained hollow alumina/silicon dioxide powder to obtain the hollow alumina/silicon dioxide powder.

Specifically, in the step (1):

controlling the mass concentration of the calcium chloride solution to be 0.05-5 g/ml;

controlling the pH value of the ammonia water adjusting system to be 8-12;

the particle size of the nano calcium carbonate template particles is controlled to be 5-500 nm.

Specifically, in the step (1), the calcium chloride template solution is added into high-speed magnetic stirring through an ultrasonic atomizer, the diameter of an ultrasonic atomization sheet is controlled to be 18mm, the vibration frequency is controlled to be 1.7MHz, and the atomized liquid drops can form nano calcium carbonate template particles with the size of 5-500nm in an alkaline reaction system.

Specifically, in the step (2),

controlling the dispersion concentration of the template particles to be 0.03-0.8 g/ml;

controlling the pH value of the ammonia water adjusting system to be 9-13;

the organic silicon comprises silane and at least one of compounds of the silane and alcohols, halogenated silane, silicon ether and silicone;

specifically, the silane includes tetramethylsilane, tetraethoxysilane, diethylsilane or dimethyldichlorosilane.

In the step (2), the reaction temperature of the reaction of the nano calcium carbonate and the organic silicon solution is controlled to be 40-80 ℃.

Specifically, in the step (3):

controlling the dispersion concentration of the silica particles with the templates to be 0.05-1 g/ml;

controlling the dispersion concentration of the silicon dioxide particles to be 0.01-0.5 g/ml;

controlling the particle size of the silica sol to be 5-10nm and the content to be 10-30%;

the mass ratio of the silica sol to the silica particles is 0.001-0.1: 1.

specifically, in the step (4):

controlling the dispersion concentration of the hollow silica particles to be 0.01-0.8 g/ml;

controlling the concentration of the ammonium bicarbonate solution to be 0.01-5 g/ml;

controlling the concentration of the water-soluble aluminum salt solution to be 0.01-5 g/ml;

the water-soluble aluminum salt comprises one or a mixture of two of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum ammonium sulfate and sodium metaaluminate and aluminum isopropoxide;

controlling ammonia water to adjust the pH value of the reaction system to 9-13.

In the step (3), the reaction temperature of the hollow silica particles and the ammonium bicarbonate is controlled to be 60-100 ℃.

Specifically, in the step (4), the calcination step includes a first calcination step at 300 ℃ under 100-.

Specifically, the preparation method of the low dielectric constant hollow alumina/silica nanocomposite comprises the following steps:

in the step (1), a step of adding a surfactant into the calcium chloride solution is further included; controlling the mass ratio of the calcium chloride to the surfactant to be 5-40: 1;

in the step (2), a step of adding a surfactant into the nano calcium carbonate template particle dispersion liquid is further included, and the mass ratio of the nano calcium carbonate to the surfactant is controlled to be 5-20: 1.

specifically, the type of the surfactant comprises one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium hexadecyl sulfate, hexadecyl trimethyl ammonium chloride and hexadecyl trimethyl ammonium bromide.

The invention also discloses application of the low-dielectric-constant hollow alumina/silicon dioxide nano composite material in the field of 5G communication.

The low-dielectric-constant hollow alumina/silica nanocomposite is a laminated shell structure with a closed cavity structure, alumina is directionally deposited on the outer surface of a hollow silica shell, an inner shell of the hollow silica shell is a silica layer, and an alumina shell is deposited and grown on the surface of the silica layer, so that the advantages of the alumina and the silica are effectively combined, the advantages of the hollow silica such as low dielectric constant, low refractive index and high-frequency dielectric stability can be simultaneously exerted, and the advantages of the alumina material such as high strength, chemical erosion resistance, small thermal conductivity, low thermal expansion coefficient and the like are utilized; the service performance of the hollow nano composite material is greatly improved, the defects of non-ideal strength and hardness, slightly poor chemical erosion resistance and the like of a single hollow silicon dioxide material are effectively overcome, the hollow silicon dioxide composite material is more suitable for outdoor environment application, and the service life of a device is greatly prolonged.

The hollow alumina/silica nano composite material has low refractive index, low dielectric constant, high strength, high hardness, low thermal conductivity, low thermal expansion coefficient and higher stability, can meet the performance requirements in the fields of antireflection and 5G millimeter wave frequency bands, and can be used in the application fields of 5G communication consumer electronic chip packaging ceramic substrates, glass ceramic co-fired substrates, antireflection high-transmittance coatings and the like.

The hollow alumina/silicon dioxide nano composite material has good dispersion performance, and can be uniformly dispersed in organic solvents such as pure water, ethanol, acetone and the like through processes such as grinding dispersion, ultrasonic treatment and the like.

Drawings

In order that the present disclosure may be more readily and clearly understood, the following detailed description of the present disclosure is provided in connection with specific embodiments thereof and the accompanying drawings, in which,

FIG. 1 is a schematic view of a hollow alumina/silica nanocomposite model according to the present invention;

FIG. 2 is a TEM image of a sample prepared in example 1 of the present invention;

FIG. 3 is a TEM image of a sample obtained in example 2 of the present invention.

Detailed Description