The Physical Effects of Intra-Drive Particulate Contamination on the Head-Disk Interface in Magnetic Hard Disk Drives

1999 ◽  
Vol 121 (2) ◽  
pp. 352-358 ◽  
Author(s):  
Kenneth J. Altshuler ◽  
Joshua C. Harrison ◽  
Evelyn Ackerman
Keyword(s):  
Surface Characterization ◽  
Hard Disk Drives ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Contributing Factors ◽  
Physical Damage ◽  
Track Width ◽  
Disk Interface ◽  
Particulate Contamination ◽  
Magnetic Hard Disk

The physical damage at the Head-Disk Interface (HDI), caused by common ceramic particles found in the manufacturing environments of the heads and disks in hard magnetic disk drives, is reported. The need for this study arises from industry wide reliability problems due to particulate induced damage at the HDL The intent of this study is to characterize the head/disk damage caused by 1 μm diamond, 1–2 pm Tie particles, 0.2–1 μm alumina particles, the alumina and TiC grains sintered to make Al-TiC (the slider body), and sputtered alumina. These particles were introduced to the HDI in over thirty disk drives. The drives were then made to perform magnetic recording and retrieval operations for known data sequences, with the resultant reading errors tabulated. After the functional testing, the drives were opened and resulting damage was examined with a number of surface characterization tools. This study confirms that the severity of problems with the read-back signal, caused by particle damage, has an inverse relationship with the magnetic track width. In addition, the harshness of physical damage to the HDI has a positive relationship with particle hardness. Finally, particle shape and size can be contributing factors in damaging the HDL.

On the Touchdown-Takeoff Hysteresis Observed at the Head-Disk Interface in Hard Disk Drives

2005 ◽  
Author(s):  
Rohit P. Ambekar ◽  
David B. Bogy
Keyword(s):  
Experimental Approach ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Intermolecular Forces ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Contributing Factors ◽  
Factors Affecting ◽  
Disk Interface

The touchdown-takeoff velocity hysteresis observed in hard disk drives during CSS or L/UL tests is analyzed using an experimental approach. Tests similar to L/UL were conducted for different slider-disk combinations at different humidities. Factors affecting the touchdown and takeoff velocity were identified on the basis of their domain of operation. It is concluded that the intermolecular forces and meniscus forces are contributing factors to hysteresis, which is also influenced by disk topography and slider dynamics.

Contact Take-Off Characteristics of Proximity Recording Air Bearing Sliders in Magnetic Hard Disk Drives

1999 ◽  
Vol 121 (4) ◽  
pp. 948-954 ◽  
Author(s):  
Yong Hu
Keyword(s):  
Hard Disk Drives ◽  
Air Bearing ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Taper Angle ◽  
Wear Factor ◽  
Disk Interface ◽  
Partial Contact ◽  
Magnetic Hard Disk ◽  
Wear Law

A partial contact air bearing model and Archard’s wear law are used to investigate the air bearing and wear characteristics of proximity recording sliders during a take-off process. The air bearing pitch torque, pitch and contact force are used to characterize the contact take-off process. In addition, the wear factor derived from the Archard’s wear law is employed to measure the take-off performance. The results indicate the existence of two distinct take-off stages: a period of rapidly increasing pitch preceding a relatively steady take-off event. The proper range of taper angle and step height, which produce a rapid initial pitch increase and steady subsequent take-off as well as less wear in the head/disk interface, are determined through simulation. While the simulation results demonstrate the negligible effect of crown height on the rate of the initial pitch increase, larger crown values are shown to yield higher pitch and smaller wear in the head/disk interface during the take-off process. In summary, the partial contact air bearing simulation and the wear factor calculation of the take-off process, developed in this study, offers a fast and accurate analytical tool to optimize ABS design for the fast take-off performance.

Boundary Effect on Particle Motion in the Head Disk Interface

2007 ◽  
Author(s):  
Nan Liu ◽  
David B. Bogy
Keyword(s):  
Drag Force ◽  
Particle Motion ◽  
Boundary Effect ◽  
Hard Disk Drives ◽  
Areal Density ◽  
Air Bearing ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Bearing Surface ◽  
Disk Interface

Simulation of particle motion in the Head Disk Interface (HDI) helps to understand the contamination process on a slider, which is critical for achieving higher areal density of hard disk drives. In this study, the boundary effect—the presence of the slider and disk—on particle motion in the HDI is investigated. A correction factor to account for this effect is incorporated into the drag force formula for particles in a flow. A contamination criterion is provided to determine when a particle will contaminate a slider. The contamination profile on a specific Air Bearing Surface is obtained, which compares well with experiments.

Effect of Non-Operational Shock on Interaction Between Suspension Lift-Tab and Load/Unload Ramp

2005 ◽  
Author(s):  
Aravind N. Murthy ◽  
Eric M. Jayson ◽  
Frank E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Failure Modes ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Areal Density ◽  
Disk Drive ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Operational Shock

Most hard disk drives manufactured in the last few years have Load/Unload (L/UL) technology. As opposed to the Contact Start/Stop (CSS) technology, L/UL technology has the advantage of improved areal density because of more disk space availability and better shock performance. The latter characteristic has significant benefits during the non-operational state of the hard disk drive since head/disk interactions are eliminated and the head is parked on a ramp adjacent to the disk. However, even if head/disk interactions are absent, other failure modes may occur such as lift-tab damage and dimple separation leading to flexure damage. A number of investigations have been made to study the response of the head disk interface with respect to shock when the head is parked on the disk ([1], [2]). In this paper, we address the effect of non-operational shock for L/UL disk drives.

Experimental Investigation of Heat Flux at the Head-Disk Interface in Hard Disk Drives

2016 ◽  
Author(s):  
Yuan Ma ◽  
David B. Bogy
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Strong Increase ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Contact Points ◽  
Phonon Conduction

In hard disk drives (HDDs), Thermal Fly-Height Control (TFC) is used to control the head disk spacing for reading or writing data. In order to monitor the spacing and detect possible contacts between the head and disk, a resistive temperature sensor, called Touch-Down Sensor (TDS), is embedded in the slider near potential contact points of the slider against the disk. Understanding the mechanisms of heat transfer across the head-disk interface (HDI) is of major importance, because it is closely related to the design of HDDs, including lubricant flow and contact issues, especially for Heat Assisted Magnetic Recording (HAMR) drives. In this paper, we conducted a series of experiments both on rotating and on non-rotating disks with TDS to find the cause of head temperature change and to validate the heat transfer theory based on phonon conduction. From the experiment, it is shown that air bearing cooling is not responsible for the cooling that occurs in the last nanometer before contact. Based on phonon conduction predictions, we should expect a decrease in slope of the non-contact curve as the spacing becomes less than 1 or 2 nm because of the strong increase in the heat flux due to phono conduction in this range.

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