ESD testing of head stack assemblies used in magnetic recording hard disk drives

Magnetic recording and optical recording are the major technologies used to provide long-term storage of information in today's computer systems. Magnetic recording has been used for data storage in computer systems for over 40 years, and the advances in technology that have occurred in that time frame are nothing short of phenomenal. One might expect that after 40 years of dominance, the rate of progress in magnetic recording would be slowing down and that other technologies would be moving in to replace it. However rather than slowing down its rate of progress, magnetic recording is now advancing at a faster rate than at any time in the past. Magnetic hard-disk drives represent the largest segment of the data-storage business, and the number of hard-disk drives sold is increasing at about 20% per year. Tape drives continue to enjoy a very substantial market and are also advancing at a rapid pace while flexible disk drives continue to appear in every personal computer sold and have recently increased capacity by nearly two orders of magnitude.Optical recording was introduced into the marketplace in 1989 and has secured a significant market. However thus far, optical recording has primarily found new market niches, rather than being directly competitive with magnetic recording. CD-ROMs are widely used for the distribution of prerecorded information—a business that is now comparable in size to the magnetic-tape-drive business. On the other hand, erasable, optical drives, which were first introduced in 1989, have not had nearly as much success and have much smaller markets than either magnetic hard drives or tape drives.

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Thermal Lagging of Multilayered Structure in Heat-Assisted Magnetic Recording Systems

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4046022 ◽

2020 ◽

Vol 12 (3) ◽

Author(s):

Jian Su ◽

Tingting Tang ◽

Ruixin Lu ◽

Peng Yu

Keyword(s):

Temperature Gradient ◽

Thermal Resistance ◽

Magnetic Recording ◽

Heat Sink ◽

Hard Disk Drives ◽

Hard Disk ◽

Interfacial Thermal Resistance ◽

Disk Drives ◽

Horizontal Temperature Gradient ◽

Heat Assisted Magnetic Recording

Abstract In the present study, we numerically investigate the thermal lagging behavior on the hard disk drives in heat-assisted magnetic recording systems via the optical absorption model. The influences of overcoats, laser radius, relative scanning speed, interfacial thermal resistance, and the heat sink layer on the thermal lagging behavior are studied in detail. It is found that the thermal lagging distance, i.e., the horizontal distance between the location of the maximum temperature and the laser center, increases with an increment of speed and/or radius of the laser spot. The overcoats, the interfacial thermal resistance, and the heat sink layer have negligible effects on the lagging distance. Thus, the multilayered disk can be simplified as a single-layer disk for investigating thermal lagging distance. Meanwhile, the horizontal temperature gradient varies with these factors. Different overcoats result in different horizontal temperature gradient owing to the difference of in-plane thermal diffusivity. A laser with a smaller radius or a slower speed leads to a higher horizontal temperature gradient. The thermal resistance influences the horizontal temperature gradient insignificantly. This study may provide useful information for the design of hard disk drives for heat-assisted magnetic recording technologies.

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ChemInform Abstract: Development of High Density Magnetic Recording Media for Hard Disk Drives: Materials Science Issues and Challenges

ChemInform ◽

10.1002/chin.201030274 ◽

2010 ◽

Vol 41 (30) ◽

pp. no-no

Author(s):

G. W. Qin ◽

Y. P. Ren ◽

N. Xiao ◽

B. Yang ◽

L. Zuo ◽

...

Keyword(s):

Magnetic Recording ◽

Materials Science ◽

Hard Disk Drives ◽

Hard Disk ◽

High Density ◽

Recording Media ◽

Disk Drives ◽

Magnetic Recording Media ◽

High Density Magnetic Recording

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Load/Unload Systems With Multiple Flying Height States

Journal of Tribology ◽

10.1115/1.1576426 ◽

2004 ◽

Vol 126 (2) ◽

pp. 367-371 ◽

Cited By ~ 7

Author(s):

M. Suk ◽

O. Ruiz ◽

D. Gillis

Keyword(s):

Magnetic Recording ◽

Hard Disk Drives ◽

Hard Disk ◽

Flying Height ◽

Critical Parameters ◽

Disk Drives ◽

Unloaded State ◽

Recording Process ◽

Loaded State ◽

Proper Operation

In hard disk drives that utilize load/unload technology, the slider loads onto the disk from hundreds of microns away before the slider settles into the designed flying height. Due to the forces acting on the slider after the transition from the unloaded state to the fully loaded state, the resulting flying height of the slider may be about two orders of magnitude higher than the intended nominal flying height. Under certain circumstances, the slider may never reach the nominal flying height required for proper operation of the magnetic recording process. In this paper, the existence of multiple flying heights is demonstrated and verified both by experimentation and simulation. The effect of some of the critical parameters is also identified by both methods. We show that necessary care must be taken to avoid unwanted loading sequences where the system may be unable to store or retrieve data.

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HAMR HDD Shock Responses

ASME 2013 Conference on Information Storage and Processing Systems ◽

10.1115/isps2013-2896 ◽

2013 ◽

Cited By ~ 1

Author(s):

Lidu Huang ◽

Kenzi Suzuki ◽

Fu-Ying Huang ◽

Toshiki Hirano ◽

Barry Stipe

Keyword(s):

Solid State ◽

Laser Diode ◽

Magnetic Recording ◽

Hard Disk Drives ◽

Hard Disk ◽

Cost Advantage ◽

Disk Drives ◽

Solid State Drive ◽

Lift Off ◽

Operational Shock

Heat assisted magnetic recording (HAMR) and slim mobile hard disk drives (HDD) are being developed parallelly to maintain cost advantage over the solid state drive (SSD). Operational shock and non-operational shock capabilities are seriously challenged for the slim HDDs due to reduced stiffness (thickness). It is worse for slim HAMR drives due to additional laser diode (LD) and other necessities being added on slider. Shock tests are part of the key performance matrices that must be passed in HDD reliability tests, and the concerns for HAMR mobile drives are, 1) slider lift-off G-level degradation during op-shock, and 2) LD back-to-back hitting during non-operational shock. We studied a few potential HAMR HGA designs, also analyzed a design that improves drive op-shock performances.

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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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