HD substrate materials are divided into two main categories: Ni-P plated aluminum and glass. The surfaces of both materials undergo mirror polishing using the abrasive materials ceric oxide, alumina and colloidal silica. The substrates are ultimately polished to an average surface roughness measured at the Å (Angstrom) level. If the microscopic foreign substances produced by polishing are not completely cleaned away, the surface after the magnetic and lubricating layers are formed will be dimpled, leading to defects that can cause the magnetic head to come into contact with the HD material. Substrate cleaning standards have been growing stricter, reflecting the accelerating pace of HD miniaturization and boosts in capacity in recent years.
Standard particle cleaning mechanisms involve removing abrasive material particles with the excess substrate material after the substrate has been surface etched. However, the unique properties of Lion’s detergents include the ability to exert selective actions on particles, eliminating the possibility of excessive substrate corrosion.
In addition, increasing the zeta potential of abrasive molecules is highly effective in preventing particles from redepositing on the cleaned surfaces.
|Properties||G sub cleaning||Cleaning after polishing (Particle detachment type)||Cleaning after polishing (Particle dispersion type)|
|pH||7.5(Liquid concentrate)||13.5(Liquid concentrate)||13.0(Liquid concentrate)|
|BOD(as is, g/l)||-||2.9||3.6|
|COD(as is, g/l)||-||6.4||4.2|
|Recommended concentration for use (%)||0.1~0.5||0.5~3||0.5~3|