Thermal fly-height controlled glide for disk defect detection and defect size estimation for hard disk drives

Current hard disk drives (HDD’s) use thermal fly-height control (TFC) during read/write operations. In this study, we use TFC technology during the disk glide process to determine sub-5nm height defects. We also utilize TFC to measure the height of the defect during glide operation. Addtionally, we magnetically mark the disk locations where defects are detected for further post-processing of the defects using optical surface analysis (OSA), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The defect height estimation during the glide was confirmed to be accurate by AFM and SEM analysis. Finally, we will present the TFC glide sensitivity showing capability of detecting smaller defects than conventional non-TFC glide technologies.

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S1604-1-5 Study on Hysteresis Behavior of Thermal Fly-Height Control Sliders in Hard Disk Drives

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2010.5.0_131 ◽

2010 ◽

Vol 2010.5 (0) ◽

pp. 131-132

Author(s):

Norio TAGAWA ◽

Satoshi MAENO ◽

Hiroshi TANI

Keyword(s):

Hard Disk Drives ◽

Hard Disk ◽

Disk Drives ◽

Hysteresis Behavior ◽

Height Control ◽

Fly Height

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Numerical and Experimental Investigation of Nanoscale Heat Transfer in the Head-Media Interface During Static Touchdown

ASME 2019 28th Conference on Information Storage and Processing Systems ◽

10.1115/isps2019-7448 ◽

2019 ◽

Author(s):

Siddhesh V. Sakhalkar ◽

Qilong Cheng ◽

Yuan Ma ◽

Amin Ghafari ◽

David B. Bogy

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Magnetic Recording ◽

Hard Disk Drives ◽

Hard Disk ◽

Disk Drives ◽

Nanoscale Heat Transfer ◽

Fly Height ◽

Head Temperature

Abstract With minimum fly height of less than 10 nm in contemporary hard-disk drives, understanding nanoscale heat transfer at the head-media interface is crucial for developing reliable head and media designs. Particularly, with the emergence of Heat-Assisted Magnetic Recording (HAMR) and Microwave-Assisted Magnetic Recording (MAMR), head failure due to overheating has become an increasing concern. There is a need to develop a methodology to use theoretical curves for spacing-dependent nanoscale heat transfer coefficient to predict head and media temperatures in actual hard disk drives. In this study, we present a numerical model to simulate the head and media temperature profiles during static touchdown and compare our results with experiments performed with a magnetic head on a silicon wafer. As the head approaches touchdown with increasing TFC power, the phonon conduction heat transfer coefficient between the head and the substrate increases exponentially, causing a drop in the head temperature vs TFC power curve. Our model shows that the introduction of van der Waals forces between the head and the substrate causes a steeper drop in the head temperature curve and ensures a good quantitative match with experimental results.

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Effects of Laser Textured Disk Surfaces on a Slider’s Flying Characteristics

Journal of Tribology ◽

10.1115/1.2834421 ◽

1998 ◽

Vol 120 (2) ◽

pp. 266-271 ◽

Cited By ~ 10

Author(s):

Yong Hu ◽

David B. Bogy

Keyword(s):

Hard Disk Drives ◽

Hard Disk ◽

Disk Drive ◽

Dynamic Responses ◽

Disk Drives ◽

Landing Zone ◽

Pressure Profiles ◽

Texture Parameters ◽

Magnetic Hard Disk ◽

Fly Height

Recently, laser texturing has captured the attention of head/media interface engineers in the hard disk drive industry because it provides precision in the landing zone placement while eliminating the transition zone of a mechanically textured landing zone. It also offers excellent tribological performance in terms of low CSS stiction and good durability. These advantages make it the solution of choice for high-end magnetic hard disk drives. This paper models the effects of laser bumps and laser textured disk surfaces on the Headway AAB slider’s flying characteristics. Two commonly used laser bump profiles (“Sombrero” and “Volcano” types) and various texture patterns are numerically generated in the simulator. The slider’s dynamic responses to these moving laser bumps and textures under two outer rail flying conditions are simulated, and the effects of various bump/texture parameters on the slider’s fly height, pitch, roll and their modulations are discussed. The laser texture mechanism is explained by examining the air bearing pressure profiles induced by the moving laser textures.

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Dimension Effect of Embedded Contact Sensor on Disk Defect Detection

ASME 2013 Conference on Information Storage and Processing Systems ◽

10.1115/isps2013-2895 ◽

2013 ◽

Author(s):

Masaru Furukawa ◽

Junguo Xu ◽

Jianhua Li

Keyword(s):

Defect Detection ◽

Thermal Contact ◽

Hard Disk Drives ◽

Defect Size ◽

Contact Detection ◽

Disk Drives ◽

Magnetic Head ◽

Head Slider ◽

Contact Sensor

A thermal contact sensor embedded in a magnetic-head slider was developed. The sensor has been used for contact detection between a head slider and a disk in hard disk drives, and, our previous research has shown that the sensor could successfully detect disk defects including asperities and pits. In this work, the sensor dimension effect and characterization of defect size was studied in order to better understanding of defect size. The results showed that the defect size can be clarified by considering sensor size and scan pitch.

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