Effect of corrosion inhibitors in lubricant for electronic industry

Abstract

The selected functional polymers and fatty esters of poly)1-butene pyrrolidone) (PP) and propylene glycol monostearate (PG) were investigated and applied to use as the corrosion inhibitors for protecting material removal during read/write head lapping processes in hard disk drive (HDD) production. Potentiodynamic polarization measurement was used to study their corrosion behaviors against antiferromagnetic materials (IrMn) which are the most sensitive materials in the head structure. Corrosion rate of PP- and PG-modified lubricants were 0.086 and 0.084 Å/min, respectively, while standard lubricant was 0.111 Å/min. Moreover, the leaching out of metallic atoms was investigated by using inductively couple plasma mass spectroscopy (ICP-MS). Leaching out of metallic atoms was in range 3-7 µg/L for PP- and PG-modified lubricant but, standard lubricant was 4-15 µg/L. The results showed that corrosion rate can be reduced compared to the standard glycol-based lubricant. The conductivity and acid-base properties of the modified lubricants were also measured and analyzed. Scanning electron microscopy (SEM) showed that the protection of those inhibitors came from the formation of protective thin layer over the surface by their functional groups. Furthermore, the electrical performance parameters from quasi static test (QST) and lapping test indicated a better lapping performance, without losing quality and electrical performance of the slider. We propose that PG and PP are the 1st and 2nd choice of additional additives in corrosion protection of IrMn material in HDD slider fabrication process.