Mineralogically speaking, sapphire is a type of corundum（Al2O3：aluminum oxide）. Sapphire has a Mohs hardness of 9, which is the next hardest material to diamond, making it very difficult to process. The material called alumina ceramics is also described with same chemical formula. However, it is the same as the difference between diamond and carbon. A single-crystal structure is categorized as sapphire, and a polycrystalline structure is categorized as alumina ceramics.。
Synthetic high-grade, single-crystalline sapphire is widely used for industrial purposes. Sapphire as jewelry is made of alumina (Al2O3). With a hint of chrome it becomes a red-colored ruby, and with a hint of iron (Fe) or titanium (Ti) it becomes blue colored. In contrast, sapphire for industrial purposes has a high-grade, clear and colorless, single-crystalline structure and has been treated.
Previously, sapphire was a material which was not suitable for high-volume production. However, advances in technology have made it possible to stably mass-produce sapphire at a reasonable price. The leading manufacturing method of sapphire is EFG (Edge-defined Film-fed Growth). In this method, the seed crystal is pulled out of the melt very slowly in order to grow the desired crystal axis and crystal face. Currently, Φ6 inch sapphire production has become common, and its use in industrial applications is further expanding.
Thanks to its superior properties, sapphire is processed and widely used in products such as the dial window of watches and the phonograph needles of record players. Recently, it has gained attention as a key material for the protection of smartphone camera lenses such as the iPhone and as a substrate for blue/green LED.
DISCO’s grinders (grinding by grinding wheel) and laser saws (dicing by laser) have been used for the thinning and dicing of sapphire wafers during device production,