Application and market of silicon powder
Silicon micropowder is a kind of non-toxic, odorless and non-polluting silica powder processed by grinding, precision classification, impurity removal, high-temperature spheroidization and other processes as raw materials of crystalline quartz, fused quartz, etc. It is an inorganic non-metallic material with excellent properties such as high heat resistance, high insulation, low linear expansion coefficient and good thermal conductivity.
Classification and varieties of silica powder
Purity (%) by use and w(SiO2): ordinary silicon powder (>99%), electrical grade silicon powder (>99. 6%), electronic grade silicon powder (>99. 7%), semiconductor grade silicon powder (>99.9%) etc.
According to chemical composition: pure SiO2 silicon powder, composite silicon powder with SiO2 as the main component, etc.
According to particle shape: angular silicon powder, spherical silicon powder, etc.
In addition, there are classifications based on particle size, surface activity, etc.
- Angular silicon powder
According to the types of raw materials, it can be further subdivided into crystalline silicon powder and fused silicon powder.
Crystalline silicon powder is a silica powder material made of quartz block, quartz sand, etc., which is processed through grinding, precision classification, and impurity removal. It improves the linear expansion coefficient and electrical properties of copper clad laminates and epoxy resins. The performance of packaging materials and other products.
Fused silica powder is made of fused silica, glass, etc. as raw materials, and is made through grinding, precision classification and impurity removal processes, and its performance is greatly improved compared with crystalline silica powder.
- Spherical silica powder
Using selected angular silicon micropowder as raw material, it is processed into spherical silica powder material by flame method and other processes. It has excellent characteristics such as good fluidity, low stress, small specific surface area and high bulk density.
Compared with spherical silicon powder, the production process of angular silicon powder is relatively simple, and the application field is relatively low, so the value is relatively low; while spherical silicon powder has better fluidity, it can be used as a filler to obtain higher filling rate and uniformity, and the price Relatively high, so the price is 3 to 5 times that of angular silicon powder.
Spherical silicon powder is classified according to its particle size and can be divided into three types: micron spherical silicon powder (1-100μm), submicron spherical silicon powder (0.1-1.0μm) and nano-spherical silicon powder (1-100nm).
With the rapid development of the global electronic information industry and the continuous improvement of 4G, 5G and other technologies, higher technical requirements have been put forward for the lightness, thinness and shortness of electronic products, the packaging performance of the chip and the carrier board for carrying the chip. The spherical silicon micropowder is also moving towards Development in the direction of small particle size and excellent performance. Submicron spherical silica powder has the advantages of small particle size, proper particle size distribution, high purity, smooth surface and no agglomeration between particles, which can make up for the shortcomings of micron spherical silica powder.
Preparation methods of submicron spherical silicon powder: gas phase method, chemical synthesis method, flame method, self-propagating low-temperature combustion method, VMC method… …
Gas phase method：the prepared product contains high impurities such as HCI and low pH. It cannot be used as the main material in electronic products. It can only be added in a small amount to adjust the viscosity and increase the strength. In addition, the raw materials are expensive, the equipment requirements are high, and the technology More complicated.
Chemical synthesis method：the prepared sub-micron spherical silicon powder is usually low in density, often contains more pores, resulting in a large specific surface area, and there are disadvantages such as the production process is not environmentally friendly.
Flame method：The raw materials used are silicon-source organics, and the safety design requirements of the feed system are stricter and the price of the raw materials is higher, which often results in higher production costs.
Self-propagating low-temperature combustion method：large-scale industrial production has not yet been achieved, and whether it can be industrialized requires further verification.
VMC method：the sub-micron spherical silica powder prepared from metallic silicon has the characteristics of smooth surface and high amorphous content. However, the raw material metallic silicon used is prone to dust deflagration, and there is a greater safety hazard in the production process.
Application and market overview of silicon powder
As a functional filler, silica powder products have unique physical and chemical properties such as high heat resistance, high insulation, low linear expansion coefficient and good thermal conductivity. They can be widely used in copper clad laminates, epoxy plastic packaging materials, electrical insulation materials, adhesives, Ceramics, coatings, fine chemicals, advanced building materials and other fields have penetrated deeply in consumer electronics, household appliances, mobile communications, automotive industry, aerospace, defense and military industry, wind power and other industries. The good development prospects of the downstream application industry provide a good guarantee for the market growth space of the silicon powder industry.
- Copper Clad Laminate
Copper clad laminate is an electronic basic material made by impregnating glass fiber cloth or other reinforcing materials with a resin matrix, one or both sides with copper foil and hot pressing. Fillers are required between the base material and the reinforcing materials. In order to improve the heat resistance and reliability of the printed circuit board (PCB board).
Silicon micropowder has excellent performance in reducing linear expansion coefficient, reducing dielectric properties, improving thermal conductivity, and high insulation. Adding silicon micropowder can improve the physical properties of printed circuit boards such as linear expansion coefficient and thermal conductivity, thereby effectively improving the performance of electronic products. Reliability and heat dissipation; and because the silicon powder has good dielectric properties, it can improve the quality of signal transmission.
At present, the filling ratio of resin in industry practice is about 50%, and the filling ratio of silicon powder in the resin is generally 30%, that is, the weight ratio of silicon powder in the copper clad laminate can reach 15%.
Copper clad laminate is a basic electronic material, and PCB is the key support for circuit components and devices in electronic products, and it is the main downstream industry of copper clad laminate. At present, PCB output value in Asia has accounted for more than 90% of the world’s total, and China’s PCB output value has accounted for more than 50%.
- Epoxy molding compound
Epoxy molding compound is a key material used to encapsulate chips in electronic products. The filling ratio of silicon micropowder in epoxy molding compound is between 70% and 90%. Taking the average filling ratio of 80% for calculation, the market capacity of silicon micropowder in the domestic epoxy molding compound industry is 80,000 tons.
High-performance integrated circuits have high requirements for materials, and the penetration rate of high-end silicon powder continues to increase. Ultra-large-scale and ultra-large-scale integrated circuits represented by high-end chips have extremely high requirements for packaging materials, not only requiring the use of ultra-fine fillers in packaging materials, but also requiring high purity and low radioactive element content. Traditional angular silicon micropowders have been difficult to meet the requirements. . Spherical silicon powder, especially sub-micron products, has excellent properties such as high heat resistance, high humidity resistance, high filling rate, low expansion, low stress, low impurity, and low friction coefficient, making it indispensable in ultra-large-scale and ultra-large-scale integrated circuit packaging materials. Missing functional filling materials. Therefore, the domestic semiconductor design, manufacturing, packaging and testing and other links continue to be replaced by localization, and the demand for high-end silicon powder has also grown rapidly.
- Demands for honeycomb ceramics, coatings, and high-end building materials are all in force
The main raw materials of honeycomb ceramic products are talc, microsilica powder, alumina, kaolin, cellulose, etc., and microsilica powder for coatings has also increased objectively. Silica powder has a similar structure to titanium dioxide, has excellent performance and low cost, and can effectively replace titanium dioxide.
Benefiting from the implementation of national environmental protection standards, industries such as environmentally friendly adhesives and artificial quartz panels have obtained better development opportunities. Special adhesives used in bridges and high-rise buildings, automotive ignition coil packaging, wind turbines and other fields have quickly obtained With the development, the high-end artificial quartz board industry has also improved. In addition, with the promotion of the country’s circular economy and the upgrading of the green environmental protection industry, artificial marble is expected to continue to replace traditional ceramic tiles and natural stones and become a new type of advanced environmentally friendly building materials. It is predicted that in 2025, the demand for silicon powder in the field of advanced building materials may increase by 358%.
Article source: China Powder Network