Several Approaches to Achieve High-Value Utilization of Silicon Micropowders

Silicon micro powder is a non-toxic, tasteless, and pollution-free silicon dioxide powder produced from raw materials such as crystalline quartz and fused quartz through processes including grinding, precise grading, decontamination, and high-temperature spheroidization. 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.

Application and Development Trends of Silicon Micro Powder

Silicon micropowders are widely used in industries such as paint coatings, electronic appliances, copper clad laminates, rubber, silicone rubber, honeycomb ceramics, precision casting, plastics, and refractory materials.

Through market observation, in recent years, copper clad laminates and epoxy molding compounds have occupied a large share of the mid-to-high-end market in silicon micro powder applications. The requirements for silicon micro powder have also been increasing. There is a growing demand for certain characteristics of silicon micro powder, such as continuously higher purity, finer particle size, more stringent particle size distribution requirements, spherical particle morphology, and prominent physical and chemical properties. At the same time, the product's added value will also continue to rise.

2 High-Quality Silicon Micro Powder Production Technology

Silicon dioxide powders are generally produced through a multi-step process involving the crushing, grinding, flotation, acid leaching purification, and deionized water washing of natural quartz minerals.

Further surface modification of silica fume using modifiers results in active silica fume. The active silica fume enhances the hydrophobic properties of the silica fume and improves the mechanical and chemical characteristics of the mixture and the filling system.

Electron silicon micro-powders with a Fe2O3 content of 0.0098% and a brightness of 87.5% are prepared through the ball mill friction washing process.

By analyzing the mineral composition and characteristics through process mineralogy, high-quality quartz concentrate is obtained after the mineral is crushed, milled, hydraulically classified, magnetically separated, and subjected to sulfuric acid washing. Further processing, including pollution-free milling, deionized water washing, and KH-570 modification, yields electronic-grade active silicon micropowder from the quartz sand.

Spherical silicon micropowders boast characteristics such as smaller specific surface area, better fluidity, and lower stress, primarily used as fillers in semiconductor epoxy resins, precision casting resins, precision ceramics, optical fiber materials, anti-caking agents in plastic production, polishing agents for electronic and optical devices, paint dispersants, and cosmetics. Currently, there are two main methods for producing spherical silicon micropowders: physical and chemical methods. Physical methods include flame sphericalization, high-temperature melting jetting, self-propagating low-temperature combustion, plasma, and high-temperature sintering sphericalization; chemical methods mainly include vapor phase, hydrothermal synthesis, sol-gel, precipitation, and microemulsion methods.

High-purity ultra-fine silicon dioxide powder is processed from high-purity quartz sand through special processing. It has a melting point of 1713°C, a transition temperature for α-β structure at 573°C, no cleavage, and only has a conchoidal fracture. It boasts chemical stability, high insulation and voltage resistance, breakdown voltage of 32-34 kV/mm, and a low coefficient of thermal expansion. These excellent properties make it highly applicable in the electronics information industry, power industry, paint industry, and light industry, among others. It is the preferred filler for integrated circuits, microelectronic products, and plastic encapsulation materials, as well as the main filler for dry potting materials used in power transmission and transformation.