Main application areas and characteristics of silicon micropowder
Silica powder is an inorganic non-metallic material with silicon dioxide as the main component. It is made of crystalline quartz, fused quartz, etc. as raw materials, and is processed by grinding, precision grading, impurity removal and other processes. It has excellent dielectric properties, low thermal expansion coefficient, and high thermal conductivity. It is widely used in copper clad laminates, epoxy molding compounds, insulating materials, adhesives, coatings, ceramics and other fields.
1. Copper clad laminate
Copper clad laminate is an important substrate for the manufacture of printed circuit boards with a structure of “copper foil + dielectric insulation layer (resin and reinforcement material) + copper foil”. It is an upstream basic material for various circuit systems.
The choices of fillers for copper clad laminates include silicon micropowder, aluminum hydroxide, magnesium hydroxide, talcum powder, mica powder and other materials. Among them, silicon micropowder has relative advantages in heat resistance, mechanical properties, electrical properties and dispersibility in resin systems. It can be used to improve heat resistance and moisture resistance, improve the rigidity of thin copper clad laminates, reduce thermal expansion coefficient, improve dimensional stability, improve drilling positioning accuracy and inner wall smoothness, improve the adhesion between layers or between insulating layers and copper foil, etc., so it is favored in copper clad laminate fillers.
Spherical silicon micropowder has the best performance but high cost, and is only used in the field of high-end copper clad laminates. In terms of thermal conductivity, filling, thermal expansion and dielectric properties, the performance of spherical silicon micropowder is better, but in terms of price, angular silicon micropowder is lower. Therefore, considering the comprehensive performance and cost, spherical silicon micropowder is currently mainly used in the field of high-end copper clad laminates, such as high-frequency and high-speed copper clad laminates, IC carriers, etc., and the higher the application scenario, the higher the addition ratio.
2. Epoxy molding compound
Epoxy molding compound is a powdered molding compound made of epoxy resin as base resin, high-performance phenolic resin as curing agent, silicon powder as filler, and a variety of additives. It is an essential material for semiconductor packaging such as integrated circuits (more than 97% of semiconductor packaging uses epoxy molding compound).
3. Electrical insulation material
Silicon powder used in electrical insulation products can effectively reduce the linear expansion coefficient of the cured product and the shrinkage rate during the curing process, reduce internal stress, and improve the mechanical strength of the insulating material, thereby effectively improving and improving the mechanical and electrical properties of the insulating material. Therefore, the functional requirements of customers in this field for silicon micropowder are more reflected in low linear expansion coefficient, high insulation and high mechanical strength, while the requirements for its dielectric properties and thermal conductivity are relatively low.
In the field of electrical insulation materials, single-specification silicon micropowder products with an average particle size of 5-25µm are usually selected according to the characteristics of electrical insulation products and the requirements of their production process, and high requirements are placed on product whiteness, particle size distribution, etc.
4. Adhesives
Silicon micropowder filled in adhesive resin can effectively reduce the linear expansion coefficient of the cured product and the shrinkage rate during curing, improve the mechanical strength of the adhesive, improve heat resistance, anti-permeability and heat dissipation performance, thereby improving the bonding and sealing effect.
The particle size distribution of silicon micropowder will affect the viscosity and sedimentation of the adhesive, thereby affecting the processability of the adhesive and the linear expansion coefficient after curing.
5. Honeycomb ceramics
Honeycomb ceramic carriers for automobile exhaust purification and cordierite material automobile exhaust filter DPF for diesel engine exhaust purification are made of alumina, silicon micropowder and other materials through mixing, extrusion molding, drying, sintering and other processes. Spherical silicon micropowder can improve the molding rate and stability of honeycomb ceramic products.