Optimization of Hard Disk Drive Heads Cleaning by Using Ultrasonics and Prevention of Its Damage

This paper investigates the optimization of hard disk drive heads under various experimental conditions such as ultrasonic frequency, sonication time, ultrasonic power and cleaning solvent. The ranges of frequency and ultrasonic power studied were 40 – 132 kHz and 100 – 500W respectively. Three solvents were tested to compare the cleaning efficiency and parts damage (low boiling point solvent: acetone and high boiling point solvent: N- Methyl Pyrolidone (NMP) around 200 °C and mixture of acetone 30% and NMP 70%). The best cleaning condition obtained from the experiments are 40 kHz with 5 min followed by 58 kHz 5 min followed by 132 kHz with 4 min followed by 58/132 kHz with 4 min. The removal efficiency (85%) is high for multiple frequencies with shorter cleaning time of each frequency compared to single frequency (70%) with longer cleaning time of same frequency (58 kHz). The surface damage induced by Ultrasonics at the contact area is almost 0 for the best cleaning condition irrespective of the solvent used (∼0.01% for acetone). As the power level increases, damage of parts also increases. The cavitation intensity is higher for higher power level. Therefore, the parts undergo more vibration and leads to more parts damage. The parts damage is more for acetone as compared to NMP. The result also indicates that the removal efficiency is high for Co-solvent (acetone +NMP) comapred to acetone or NMP alone. The AlTiC surface profile of the burned parts can be measured by using Atomic Force Microscope technique (AFM). The result indicates that the surface roughness value (Ra) obtained from AFM analysis for good and burned slider was 2.294 nm and 8.288 nm respectively. The Ra value was almost 4 times higher for burned slider. The defects/contamination on the AlTiC surface can be detected by using Energy Dispersive X-Ray (EDX) analysis