Laser Dry Cleaning of ZrO 2 Particles from Air Bearing Surface of Magnetic Head Sliders
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on the substrate surfaces can be removed by laser irradiation [6-8]. In this article, we report a new approach for laser dry cleaning of ZrO2 particles from air bearing surface (ABS) of magnetic head sliders. EXPERIMENTAL The schematic diagram of laser cleaning system is shown in Fig. 1. A KrF excimer laser (Lambda Physik LPX50) with a wavelength of 248 nm, a pulse width of 23 ns, a maximum pulse repetition rate of 30 Hz, and a maximum pulse energy of 300 mJ is used as a light source for laser cleaning. The laser beam after passing through an aperture is directed by a mirror and focused by a quartz lens onto magnetic head sliders. The energy of laser beam can be detected by an energy meter. Laser fluence ( pulse energy / beam area) on magnetic head sliders can be varied by either changing the beam area or laser energy. Laser energy, repetition rate and pulse number can be controlled by a computer. The contaminants on samples were introduced by coating ABS of magnetic head sliders with an acetone suspension of ZrO2 powder. A strong air jet was then applied to remove all "loose" particles. The samples are mounted on an X-Y stage. The air bearing surface (ABS), which is made of alumina titanium carbide (A1203.TiC), before and after laser cleaning was observed by an optical microscope.
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Fig.1. The schematic diagram of laser cleaning system.
RESULTS AND DISCUSSION In order to obtain higher cleaning efficiency, we investigated the relationship between the cleaning efficiency and laser parameters such as laser fluence, pulse number and repetition rate. The laser cleaning efficiency is defined as the ratio of the number of particles removed by
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Pulse number: 100 Repetition rate: 5 Hz
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Laser Fluence (mJ/cm2) Fig.2. Laser fluence dependence of laser cleaning efficiency at 100 pulses and 5 Hz for removal of ZrO2 particles from ABS (A120 3 TiC) of magnetic head sliders.
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Laser fluence: 300 mJIcm2 200 mJLcmn
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Pulse Number Fig.3. Pulse number dependence of laser cleaning efficiency at 200 mJ/cm 2 and 5 Hz, and at 300 mJ/cm 2 and 5 Hz for removal of ZrO2 particles from ABS (A1 20 3 •TiC) of magnetic head sliders.
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laser cleaning to the number of particles on the same area before laser cleaning regardless of particle size. A number of magnetic head sliders with ZrO2 particles on ABS were prepared. The particle density on ABS of magnetic head sliders is about 1000 mm 2 , therefore, it is statistically accurate enough to calculate laser cleaning efficiency from the particle number counted in the area of optical micragraph with a magnification from 200 to 800.
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Repetition Rate (Hz) Fig.4. Repetition rate dependence of laser cleaning efficiency at 1000 pulses and 200 mJ/cm 2 for removal of ZrO2 particles from ABS (A120 3 , TiC) of mag
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