The current application status of crystalline silicon micro powder

   Crystalline silicon micro powder (SiO2) is a widely used inorganic non-metallic material, which has excellent dielectric properties, low thermal expansion coefficient, low thermal conductivity, and corrosion resistance. Meanwhile, high-quality silicon micro powder has become one of the important and key raw materials in the high-tech field due to its excellent physical properties, extremely high chemical stability, and unique optical properties.

Crystalline silicon micropowder is made of natural quartz (SiO2) or fused silica (amorphous SiO2 of natural quartz after high temperature melting and cooling) through crushing, ball milling (or vibration, airflow milling), flotation, acid cleaning purification, high-purity water treatment and other processes.

(1) Applications in the electronics and electrical industry

At present, modern microelectronics technology is developing at an astonishing speed towards high integration, high density, and miniaturization. The rapid development of advanced packaging technology for spherical silicon micro powder has put forward increasingly high requirements for packaging materials. 70% to 90% of the epoxy plastic used for integrated circuit packaging is silicon micro powder. When the integration degree reaches 1M to 4M, it is required to add some spherical silicon micro powder, while when the integration degree reaches 8M to 16M, all spherical silicon micro powder must be used. There are electronic grade crystalline silicon micro powder, electronic grade crystalline active silicon micro powder (JGH), electronic grade molten silicon micro powder, and electronic grade molten active silicon micro powder used in the electronics industry. The product specifications are based on the number of mesh sizes, which are divided into 300, 400, 600, and 1000 mesh sizes.

(2) Application in wear-resistant rubber products

Wear resistant rubber products include rubber sheets, pipes, belts, and rollers, which require the mixed rubber to have good permeability and strong adhesion. Experimental results have shown that the mixed rubber filled with silicon micro powder fully embodies the unique properties of rubber material thinness, good permeability, good dispersion, and strong adhesion, which is conducive to the rubbing of the mixed rubber on canvas and enhances the adhesive strength between the film and canvas. The mechanical properties such as tensile strength and permanent deformation of the product are significantly improved, especially enhancing the wear resistance of rubber products.

(3) Application of Silicone Rubber Products

High quality ultrafine SiO2, due to its high whiteness, hardness, high temperature resistance, and flame retardancy, has a molecular structure similar to that of silicone rubber. It can be used as a reinforcing agent for silicone rubber, modification of resin based composite materials, as well as an additive for new plastics, organic glass, coatings, paper, and other products. It is also used for large-scale electronic plastic packaging. It can serve as infrared shielding, UV radiation resistance, high dielectric insulation, and electrostatic shielding in functional materials, and also has important applications in fields such as biomimetic materials.

(4) Other application areas

Crystalline silicon micro powder is used as an additive in the refractory material industry to prepare high-performance refractory materials. In the chemical industry, it can be used as an inert filling material in various compounds to replace silicate materials such as talc and kaolin. In the construction industry, cement admixtures can be used to reduce the water cement ratio and improve workability; Used for reinforced concrete, it can greatly improve the compactness of concrete and enhance its resistance to leakage, such as in hydropower dams, large and small water tanks, etc.

Currently, almost all silicon micro powder production enterprises in China use conventional processing equipment from non mineral industries, including crushing, grading, drying, etc. In the process, there is a lack of systematic control measures, and some enterprises adopt simple online monitoring and offline control measures, but still cannot solve the fundamental problem. As for the cleanliness of the production environment, it is even more worrying. Therefore, the purity, particle size, and stability of our country's silicon micro powder products are poor, and they have always been unable to compete with imported products from abroad. Driven by the rapid development of the domestic microelectronics industry, the amount of spherical silicon micro powder is increasing day by day. Due to the strict blockade and monopoly of foreign manufacturers on the introduction of production technology and specialized equipment for spherical silicon micro powder in China, some domestic research units such as Tsinghua University, Wuhan University, Nanjing University have started to tackle the problem since the "15th Five Year Plan". However, it is still in the laboratory stage and has not yet achieved industrial operation.