What are the advantages of boron carbide abrasives in sapphire grinding
The main purpose of the sapphire grinding process is to remove the surface cut marks and uneven damage layers produced during the sapphire slicing process, improve the flatness of the wafer, and reduce the surface roughness to meet the pre-polishing requirements. In industrial processing, the surface of sapphire needs to go through three processing processes from the rough surface of the raw material to the smooth mirror surface: rough grinding, fine grinding and polishing. After each processing process, the total thickness deviation and surface roughness of the sapphire wafer will gradually decrease.
Sapphire has high hardness, and general abrasives have no cutting force on sapphire. From the point of view of materials and grinding, the better materials for processing and grinding sapphire crystals are artificial diamond, boron carbide, and silicon dioxide. Due to the excessive hardness of artificial diamond (Mohs hardness 10), it will scratch the surface when grinding the sapphire wafer, affecting the light transmittance of the wafer, and the price is expensive, while the hardness of silicon dioxide is not enough (Mohs hardness 7), grinding The force difference is time-consuming and labor-intensive in the grinding process. Therefore, boron carbide abrasive (Mohs hardness 9.3) becomes an ideal material for processing and grinding sapphire crystals.
Boron carbide has been used as a coarse sand grinding material a long time ago. It has a high melting point, but it can be processed into simple shapes by melting powder at high temperature. Used for grinding, grinding, drilling and polishing of hard materials such as cemented carbide and gemstones.
Boron carbide abrasives have obvious advantages over diamond abrasives in reducing the damage depth of sapphire subsurface. In addition to the obvious advantages of boron carbide in rough grinding of sapphire, its composite particles with other abrasive particles are also worth exploring to improve the surface quality and processing efficiency of sapphire chemical mechanical polishing.