Abstract
A non-destructive technique to inspect a scratch on all magnetic disks in the beginning process of hard disk drive (HDD) manufacturing by using CD and DVD pick-up heads as the detector is proposed. It requires a 100% disk inspection of micrometer-sized scratches in a quick measurement with low cost inventing. Most of the previous studies were in static state but this is the first time to be done in dynamic study using the microcontroller in order to promptly serve for industrial utilization. The size, position, and shape characteristic of scratches are examined using light reflection technique. The results show that, when the laser beam is targeted on a magnetic disk in a position, either scratch or non-scratch, the reflected light intensity differs. The DVD pick-up head can detect the width and the surface characteristic of the scratches, which is similar to the results from scanning electron microscope (SEM) for all scratches sizes less than 100 µm. It is also found that using a DVD pick-up head provides a better resolution of shape characteristic and roughness of scratches surface than a CD pick-up head. Hence, the scratch size of 10s µm scale on the magnetic disk can be accurately characterized by this proposed technique, which can be further utilized for magnetic disk inspection in the hard disk drive manufacturing process.
Highlights
Scratch detection on magnetic disk is an important process of a quality inspection of hard disk drive (HDD) manufacturing because the scratches could possibly affect reading/writing performance of the HDD [1]
The radio frequency (RF) output of the CD/DVD pick-up heads is amplified by the RF summing amplifier circuit and measured by the oscilloscope
The scratches position is calculated as the rotating distance of the magnetic disk per sampling number within 1 cycle
Summary
Scratch detection on magnetic disk is an important process of a quality inspection of hard disk drive (HDD) manufacturing because the scratches could possibly affect reading/writing performance of the HDD [1]. In order to detect scratches, many tools have been employed, such as scanning electron microscope (SEM) and atomic force microscope (AFM). They were introduced because of their clarified resolution for detecting a scratch and its depth by images [3]. They are complicated in terms of utilization procedures and the light microscope with less complication than those proposed with a low resolution gain of about 100× [4]. These three methods are surface free-contact techniques, they are
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