Silicon micropowder is also an important raw material for producing polysilicon. Silicon micropowder reacts with anhydrous hydrogen chloride (HCl) in a fluidized bed reactor to generate trichlorosilane (SiHCl3), which is further purified, reduced and deposited into polysilicon in hydrogen. Polycrystalline silicon is the main raw material of solar cells in photovoltaic industry. In recent years, with the continuous shortage of global energy, the development of solar energy has become the focus of energy strategies of all countries in the world. With the surge of photovoltaic industry, the price of polysilicon, the raw material of solar cells, has soared, which has prompted the market demand for silicon micropowder to grow rapidly, and the demand exceeds supply, making silicon resource owners enjoy amazing profits. ?
According to the survey, at present, the domestic production capacity of silicon micro-powder is about 250,000 tons, mainly ordinary silicon micro-powder, while high-purity ultra-fine silicon micro-powder relies heavily on imports. It is preliminarily predicted that the demand for superfine silicon powder in China will reach more than 60,000 tons in 2005. Among them, the rubber industry is the biggest user, and the coating industry is an important application field with great potential. Electronic plastic packaging materials, silicon substrate materials, electronic and electrical castables, etc. all rely on imported high-purity ultrafine silicon powder raw materials. The price of ordinary spherical silicon powder is only 20,000-30,000 yuan/ton, while the price of high-purity ultrafine silicon powder is as high as several hundred thousand yuan/ton. ?
Silicon micropowder is made of pure quartz powder through advanced superfine grinding technology, and it is an inorganic nonmetallic material with extremely wide applications. It has excellent dielectric properties, low thermal expansion coefficient, high thermal conductivity and good suspension performance. Because of its excellent physical properties, high chemical stability, unique optical properties and reasonable and controllable particle size distribution, it is widely used in optical glass, electronic packaging, electrical insulation, high-grade ceramics, paints and coatings, precision casting, silicone rubber, medicine, cosmetics, electronic components, VLSI, mobile communication, notebook computers, aerospace and other production fields. ? Silicon micropowder is also an important raw material for producing polysilicon. Silicon micropowder reacts with anhydrous hydrogen chloride (HCl) in a fluidized bed reactor to generate trichlorosilane (SiHCl3), which is further purified, reduced and deposited into polysilicon in hydrogen. Polycrystalline silicon is the main raw material of solar cells in photovoltaic industry. In recent years, with the continuous shortage of global energy, the development of solar energy has become the focus of energy strategies of all countries in the world. With the surge of photovoltaic industry, the price of polysilicon, the raw material of solar cells, has soared, which has prompted the market demand for silicon micropowder to grow rapidly, and the demand exceeds supply, making silicon resource owners enjoy amazing profits. ? According to the survey, at present, the domestic production capacity of silicon micro-powder is about 500,000 tons, mainly ordinary silicon micro-powder, while high-purity ultra-fine silicon micro-powder relies heavily on imports. It is preliminarily predicted that the demand for superfine silicon powder in China will exceed 654.38 million tons in 2008. Among them, the rubber industry is the biggest user, and the coating industry is an important application field with great potential. Electronic plastic packaging materials, silicon substrate materials, electronic and electrical castables, etc. all rely on imported high-purity ultrafine silicon powder raw materials. The price of ordinary spherical silicon powder is only 20,000-30,000 yuan/ton, while the price of high-purity ultrafine silicon powder is as high as several hundred thousand yuan/ton.
Ultrafine silicon powder has the characteristics of small particle size, large specific surface area, high chemical purity and good dispersibility. Because of its excellent stability, reinforcement, thickening and thixotropy, it is widely used in rubber, coating, medicine, paper making, daily chemical and other fields. , and provides the foundation and technical guarantee for the development of related industrial fields, and enjoys the reputation of "industrial monosodium glutamate" and "source of materials science". Since it came out, it has become one of the most adaptable and fastest-growing varieties in modern material science. Developed countries have taken fine inorganic materials with high performance and high added value as the focus of new materials in this century.
In recent years, the computer market and the network information technology market have developed rapidly, the CPU set is getting bigger and bigger, the operation speed is getting faster and faster, and there are more and more home computers and Internet users, so the requirements for computer technology and network technology are getting higher and higher. As a technical support, the microelectronics industry has also achieved rapid development. 、Pⅳ？ Processors and broadband large-capacity transmission networks are inseparable from the hardware support of large-scale and very large-scale integrated circuits.
With the rapid development of microelectronics industry, the requirements for large-scale and ultra-large-scale integrated circuit packaging materials are getting higher and higher, which require not only ultra-fine, but also high purity and low radioactive element content, especially spherical particle shape. High-purity ultra-fine fused spherical quartz powder (spherical silicon powder for short) has become an indispensable high-quality material in large-scale and ultra-large-scale integrated circuit substrates and packaging materials because of its excellent properties such as high dielectric, high heat resistance, high moisture resistance, high filling capacity, low expansion, low stress, low impurity and low friction coefficient.
Why spheroidize? First of all, the surface fluidity of the ball is good, and it is evenly mixed with resin to form a film. The amount of resin added is small, and the fluidity is the best. The filling amount of powder is the highest, and the weight ratio can reach 90.5%. So spheroidization means that the filling rate of silicon powder increases. The higher the filling rate of silicon powder is, the smaller its thermal expansion coefficient is, the lower its thermal conductivity is, and the closer it is to the thermal expansion coefficient of monocrystalline silicon, the better the service performance of electronic components produced by this method is. Secondly, the spherical powder plastic packaging material has the smallest stress concentration and the highest strength. When the stress concentration of corner powder plastic packaging material is 1, the stress of spherical powder is only 0.6. Therefore, when packaging integrated circuit chips with spherical powder plastic packaging materials, the yield is high, and mechanical damage is not easy to occur during transportation, installation and use. Thirdly, the spherical powder has small friction coefficient, little wear on the mold and long service life of the mold. Compared with corner powder, the service life of the die can be doubled. The packaging molds of plastic packaging materials are expensive, and some of them need to be imported, which is also very important for packaging factories to reduce costs and improve economic benefits.
Spherical silicon micropowder is mainly used for packaging large-scale and ultra-large-scale integrated circuits. Whether spherical silicon powder is used or not depends on the integration level (the number of standard components in each integrated circuit). When the integration degree is 1M to 4M, the spherical powder has been partially used, and when the integration degree is 8M to 16M, the spherical powder has been completely used. At the level of 250M, the line width of the integrated circuit is 0.25μm, and at the level of 1G, the line width of the integrated circuit has been as small as 0.18μ m. At present, the computer P Ⅳ? The CPU chip of the processor has reached this level. The spherical powder used at this time is more upscale. Ethyl orthosilicate is mainly made of polysilicon waste, which is hydrolyzed with silicon tetrachloride to obtain silicon dioxide. It is also made into a sphere with a particle size of? -( 10 ~ 20) micron adjustable. Spherical silicon micro-powder synthesized by chemical method is 10 times more expensive than spherical powder made from natural raw materials, because this powder is basically free from radioactive α-ray pollution and can reach uranium content below 0.02PPb. When the integration is high, the lead spacing between VLSI is very small, and when the packaging material is radioactive, the integrated circuit will produce source errors, which will affect the reliability of VLSI, so strict requirements must be put forward for radioactivity. And the natural seasonal raw materials reach (0.2 ~ 0.4)? PPb is a good raw material. At present, the spherical powder used in China is mainly natural raw materials and imported powder.
Integrated circuits are generally formed by etching circuits on monocrystalline silicon wafers, then connecting leads and tube corners, and then encapsulating them with epoxy plastic sealant. The closer the thermal expansion coefficient of plastic packaging materials is to monocrystalline silicon, the better the working thermal stability of integrated circuits. The melting point of monocrystalline silicon is 14 15℃, the expansion coefficient is 3.5PPM, the fused quartz powder is (0.3 ~ 0.5) ppm, and the epoxy resin is (30 ~ 50) ppm. When molten spherical quartz powder is added to epoxy resin in high proportion to make plastic packaging material, its thermal expansion coefficient can be adjusted to about 8PPM, and the more it is added, the closer it is to monocrystalline silicon wafer. Crystalline powder, commonly known as raw powder, has a thermal expansion coefficient of 60PPM and a timely melting point of 1996℃, which cannot replace fused quartz powder (i.e. fused silica micropowder). Therefore, when spherical powder is not used in high-end integrated circuits, fused angular silicon powder should also be used. This is also the reason why high-grade spherical powder can't be shaped into a nearly spherical shape with crystalline powder. Japan also walked this road in the 1980s, and the effect was not good. 10 years ago, including now, people in our country still took this road. From the above theory, it is proved that this method is not feasible. That is to say, high-grade plastic packaging powder cannot be replaced by crystalline powder.
Which is better to produce high-purity spherical quartz powder by melting or crystallization? According to experiments, experts think this problem is very clear. Spherical quartz powder can be prepared from natural silica by high temperature melting and spraying. A ball made of natural crystalline powder and then dispersed by plasma flame is a molten ball. The ball made of flame burning powder has a bright surface and a smaller volume, so it is better to use. The powder provided by Japan is completely flat by X-ray spectrum analysis, and it is also completely melted spherical quartz powder. However, domestic melting time, such as Lianyungang melting time spectrum analysis, the amorphous content is 95%, and the spectral line can still be seen, with a peak value of 5. Therefore, as long as the purity of spherical quartz powder can meet the requirements, it is best to use natural crystal as raw material, with the lowest production cost and simpler process route.
1) The application of silicon micropowder in rubber products?
Activated silica micropowder (treated by coupling agent) is filled in rubber compounds such as natural rubber and cis-polybutadiene rubber, which has the advantages of easy dispersion, good mixing performance, good calendering and extrusion performance, and can improve the vulcanization speed of vulcanized rubber and enhance the viscosity of rubber. In particular, filling superfine silica powder in rubber compound to replace part of white carbon black has a good effect on improving the physical properties of products and reducing production costs. 60-70% of -2um silica micropowder is used for export-grade medicinal chlorinated butyl rubber bottle stoppers and electrically insulating rubber shoes, and the effect is good. ?
Silicon micropowder is used as filler in imitation leather, and its technical indexes such as strength, elongation and flexibility are better than those made of inorganic materials such as light calcium carbonate, activated calcium carbonate and activated pyrophyllite. ?
Silicon micropowder is used to replace refined clay, light carbonate and other powders in battery rubber shell, and the filling amount can reach about 65%, and the process performance is good. The obtained rubber shell products have physical and mechanical properties such as smooth appearance, high hardness, acid corrosion resistance, voltage resistance, thermal deformation and impact resistance, which all reach or exceed the technical indexes of JB3076-82. ?
(2) The application of silicon micropowder in plastic products?
Activated silica micropowder is an ideal reinforcing agent for polypropylene, polyvinyl chloride, polyethylene and other products, which not only has a large filling amount, but also has good tensile strength. The masterbatch can be used for PVC floor tiles, which can improve the wear resistance of products. ?
The application of silicon micro-powder in olefin resin film has the advantages of uniform powder dispersion, good film-forming property and strong mechanical properties. Compared with the plastic film produced with PCC as filler, the infrared transmittance is reduced by more than 10%, which is widely used in agricultural greenhouse film. But also can be used in the field of outer sheathing of wires and cables. ?
(3) The application of silicon micropowder in melting instrument glass and glass fiber?
Because of its fine particles and high purity, silicon micropowder is easy to melt in glass manufacturing and production, which takes a short time. The physical and chemical properties and appearance quality of borosilicate instrument glass, sodium instrument glass, neutral utensils and other products meet the corresponding standards. At the same time, the energy-saving effect in production is particularly remarkable. ?
Moreover, according to the characteristics of fine and uniform particle size and large specific surface area, silicon micropowder is used in the new process of glass fiber direct drawing, which greatly improves the homogenization degree of glass fiber batch and accelerates the vitrification speed in the furnace. The stability of wire drawing is better than that of glass ball wire drawing process, which has obvious effects of energy saving and production cost reduction. As an energy-saving mineral raw material, the application of silicon micropowder in ceramic industry has also achieved ideal results in reducing firing temperature and improving yield. ?
(4) Is the effect of silicon micropowder as polishing and washing abrasive good?
With the development of modern science and technology, the surface treatment of materials is required to be higher and more precise, and the application of grinding is more and more extensive. Silicon micropowder particles are close to round, which is a good abrasive for cleaning metal parts. After ultrafine grading preparation, it was modified. If it is used to clean bearings, the smoothness can reach above 3.0, which is better than similar products of monitors. ?
In addition, it is used to polish semiconductor industry, precision valves, hard disks, magnetic heads and automotive polishes, and has good results?
(5) The application of silicon micropowder in coatings?
Using the unique function of silicon micropowder to replace precipitated barium sulfate and talcum powder, it can be used to prepare ready mixed paint, primer and enamel-proof paint. (6- 15%) not only plays the role of filling and compatibilization, but also improves the fineness, leveling and film hardness of the coating, shortens the grinding time of the coating, shortens the water resistance, rust resistance and corrosion resistance of the coating, and improves the dispersibility and storage stability of the coating. Furthermore, the molten film coating composed of silicon micropowder, water, surfactant and water in a certain proportion has become a high-quality coating in precision casting because of its low viscosity, no filling phenomenon and convenient use. ?
Used for cabinet facing, it has excellent decorative effect and corrosion resistance. ?
(6) The application of silicon micropowder in electrical insulation packaging materials?
Electrical grade silicon micropowder is a kind of active silicon micropowder, which can be used as epoxy resin insulating sealing filler for electrical products. It can not only greatly increase the filling amount, but also play a beneficial role in reducing the viscosity of the mixture system, improving the processability, improving the permeability of the mixture to the high-voltage electric coil, reducing the expansion coefficient and shrinkage of the cured product, supporting the thermal tension difference between the mixture and the coil, and improving the thermal, electrical and mechanical properties of the cured product. ?
As for the industry prospect of silicon micropowder, we look forward to it from the following aspects: market space? Internationally, the global annual demand for silicon powder is about 654.38+10,000 tons. Japan is the country with the largest output of epoxy plastic packaging materials in the world, and it needs 30,000 tons of silicon powder every year, all of which depend on imports. The United States needs 20,000 tons of silicon powder every year; South Korea's annual demand for silicon powder exceeds 10000 tons. ? Domestically, according to the statistics of relevant departments, the annual consumption of high-purity 300- 1000 mesh ordinary silicon powder and ultra-fine crystalline silicon powder at home and abroad keeps increasing by 20%-35%, and the demand growth will continue to increase with the expansion of application scope. ? In 200 1 year, the total consumption of smelting materials in China is 6.5438+0.8 million tons, of which 6.5438+0.2 million tons are imported. The total consumption in 2004 was 78,000 tons, of which 48,000 tons were imported. It is estimated that the total consumption will exceed 6,543,800 tons this year, and 25,000 tons have been imported in the first half of this year. The annual demand for silicon micro-powder in high-tech field is over 20,000 tons. ? It is predicted that the domestic demand for fused quartz powder will reach 1.5-0.3 million tons in 20 10; In terms of electronic products, the demand for crystalline silicon powder is expected to exceed 700,000 tons/year; In melting timely ceramics, the domestic demand for silicon powder will reach 30,000 tons per year, and the market prospect is broad. ? It is understood that China's high-grade silicon micro-powder products mainly rely on imports. With China's entry into WTO market and the rapid development of IT industry in China, the electronic packaging industry will gradually move to China. Experts predict that China will become a big packaging country in the world in the new century, and the market of downstream products such as high-purity ultrafine silicon powder will also expand. ? Profit margin? Although both products are silicon micropowder, the price difference is 108,000 miles. For example, ordinary 300-mesh silicon micropowder is only 600 yuan/ton, while the price of 8000- 10000 mesh ultra-fine high-purity electronic micropowder is as high as 100000 yuan/ton. If it is upgraded to nano-scale molten powder, the price will be as high as 200,000 yuan/ton. ? Product upside development space? Relevant units in China have successfully developed electronic-grade high-purity ultrafine silicon powder. This is an electronic material product with attractive market prospect. High-purity ultrafine silicon powder is the main raw material for large-scale integrated circuit substrates and electronic packaging materials. Can be combined with epoxy resin to complete the bonding and sealing of chips or components. The doping ratio of ultrafine silicon powder in epoxy resin determines the thermal expansion coefficient of the substrate. The higher the proportion of silicon powder, the smaller the thermal expansion coefficient of the substrate, that is, the closer it is to the thermal expansion coefficient of the silicon wafer, thus avoiding the damage of uneven expansion to the microcircuit. Therefore, there are strict requirements for the purity, fineness and particle size distribution of silicon micropowder. ? Enterprise instance? From the above analysis, it can be seen that silicon micropowder has attractive market prospects and broad development space. With the development of high technology, the demand for silicon micro-powder materials is getting higher and higher. Enterprises can adjust the product structure at any time, develop deep-processed products and improve their competitiveness with less investment according to the needs of the market. But all this must have an indispensable premise-scientific and technological innovation. Only by relying on science and technology to develop high-tech products can the market space continue to expand and form a virtuous circle.
References: