Smear growth on head slider surface from siloxane outgas on heat assisted magnetic recording

In this study, the smear by the lubricant and siloxane pickup at the laser heating in the heat assisted magnetic recording (HAMR) was evaluated using our developed noncontact pin-on-disk test. The smear area on the glass pin surface was measured on the disks with three types of different lubricant films prepared by changing the ultraviolet exposure condition, rinse condition, and lubrication process. The amount of siloxane adsorbed on disk surface relates with the siloxane wettability obtained from the contact angle of siloxane for disk surface and that increased as the siloxane wettability increases. On the other hand, the lubricant pickup increases as the physical and hydrogen bonding fractions increase. Overall, these data suggest that the sufficiently low surface free energy is needed by the lubricant film with only the chemical bonding fraction to reduce the lubricant and siloxane smear at the laser heating of HAMR, because the lubricant fractions of physical and hydrogen bonding increase the lubricant pickup and the much amount of siloxane adsorbs on disks with the large surface free energy.