scholarly journals The Head-Disk Interface Roadmap to an Areal Density of Tbit/in2

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Bruno Marchon ◽  
Thomas Pitchford ◽  
Yiao-Tee Hsia ◽  
Sunita Gangopadhyay
Keyword(s):  
Hard Disk Drives ◽  
Rotating Disk ◽  
Areal Density ◽  
Disk Surface ◽  
Inert Atmosphere ◽  
Annual Growth Rate ◽  
Head Disk Interface ◽  
Bit Patterned Media ◽  
Disk Interface ◽  
Compound Annual Growth Rate

This paper reviews the state of the head-disk interface (HDI) technology, and more particularly the head-medium spacing (HMS), for today’s and future hard-disk drives. Current storage areal density on a disk surface is fast approaching the one terabit per square inch mark, although the compound annual growth rate has reduced considerably from ~100%/annum in the late 1990s to 20–30% today. This rate is now lower than the historical, Moore’s law equivalent of ~40%/annum. A necessary enabler to a high areal density is the HMS, or the distance from the bottom of the read sensor on the flying head to the top of the magnetic medium on the rotating disk. This paper describes the various components of the HMS and various scenarios and challenges on how to achieve a goal of 4.0–4.5 nm for the 4 Tbit/in2density point. Special considerations will also be given to the implication of disruptive technologies such as sealing the drive in an inert atmosphere and novel recording schemes such as bit patterned media and heat assisted magnetic recording.

A Method for Characterizing the Head-Disk Interface Dynamics Near the Touchdown Conditions Using the Magnetic Fly-Height

2020 ◽  
Author(s):  
Rahul Rai ◽  
Abhishek Srivastava ◽  
Bernhard Knigge ◽  
Aravind N. Murthy
Keyword(s):  
Hard Disk Drives ◽  
Areal Density ◽  
Disk Surface ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Soft Contact ◽  
Disk Interface ◽  
Magnetic Spacing ◽  
Bearing Stiffness ◽  
Fly Height

Abstract Recent growth in the cloud storage industry has created a massive demand for higher capacity hard disk drives (HDD). A sub-nanometer head media spacing (HMS) remains the most critical pre-requisite to achieve the areal density needed to deliver the next generation of HDD products. Designing a robust head-disk interface (HDI) with small physical clearance requires the understanding of slider dynamics, especially when the head flies in proximity to the disk surface. In this paper, we describe a method using the magnetic read-back signal to characterize the head fly-height modulations as it undergoes a transition from a free-flying state to soft contact with the disk surface. A technique based on the magnetic fly-height sensitivity is introduced for the identification of the transition plane that corresponds to the onset of the touchdown process. Additionally, the proposed magnetic spacing based meteorology is used to study the effect of the air bearing stiffness on the magnitude of the slider vibrations induced by intermittent head-disk interactions. The information about the minimum spacing while maintaining the stable flying conditions can help in reducing the head-disk interaction risk that can enable a low clearance interface.

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.

Impact of Touchdown Detection on Bit Patterned Media Robustness

2013 ◽  
Author(s):  
Jia-Yang Juang ◽  
Kuan-Te Lin
Keyword(s):  
Areal Density ◽  
Flying Height ◽  
Head Disk Interface ◽  
Bit Patterned Media ◽  
Patterned Media ◽  
Disk Interface ◽  
Recording Process ◽  
Friction Temperature ◽  
The Media ◽  
The Impact

Bit patterned media (BPM) is considered as a revolutionary technology to enable further increase of areal density of magnetic recording beyond 1 Tbits/in2 [1]. Implementing BPM technology, however, significantly increases the complexity of the recording process, but also poses tremendous tribological challenges on the head-disk interface (HDI) [2]. One of the major challenges facing BPM is touchdown detection by thermal flying-height control (TFC), in which a minute heater located near the read/write transducers is used to thermally protrude a small portion of the slider into contact with the disk, and the contact is then detected by directly or indirectly measuring the friction, temperature rise or vibration caused by the contact [3]–[7]. Most recording heads rely on touchdown detection to achieve a desired flying height (FH), which approaches sub-1-nm regime for many of today’s commercial drives. As a result sensitive and accurate touchdown detection is of critical importance for a reliable head-disk interface by reducing contact duration and unnecessary interaction between the slider and the disk. However, the impact of touchdown on the mechanical robustness of the media has not been properly studied.

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.

A Method to Detect Head Media Spacing Change in a Hard Disk Drive Using an Embedded Contact Sensor

2019 ◽  
Author(s):  
Rahul Rai ◽  
Puneet Bhargava ◽  
Bernhard Knigge ◽  
Aravind N. Murthy
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Disk Surface ◽  
Physical Change ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Frequency Components ◽  
Contact Sensor

Abstract Growth in the demand for higher capacity hard disk drives (HDD) has pushed the requirement for head-media spacing (HMS) to sub-nanometer levels. The drop in operational clearance makes a head-disk interface (HDI) more susceptible to potential head-wear and contamination related issues. Such degradation processes are often accompanied by a noticeable shift in the head-disk clearance. Hence monitoring an interface for a spacing change can be helpful in early detection of its imminent failure. In this paper, we present a method to detect the change in head-disk spacing using an embedded contact sensor (ECS). This technique involves the analysis of ECS dynamic response for an interface that is subjected to heater induced spacing modulations. As the head moves closer to the disk surface, the magnitude of the ECS frequency components can be used to determine the ‘characteristic spacing’ which can be used as a metric to detect any physical change for a given interface.

Effect of Vapor Lubrication on Head–Disk Clearance and Slider Wear in Inert Gas Environments

2014 ◽  
Author(s):  
Hiroshi Tani ◽  
Jun Tomita ◽  
Shinji Koganezawa ◽  
N. Tagawa
Keyword(s):  
Storage Capacity ◽  
Hard Disk Drives ◽  
Disk Surface ◽  
Inert Gas ◽  
Flying Height ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Small Clearance ◽  
Vapor Lubrication

The application of dynamic flying height (DFH) control technology to hard disk drives (HDDs) reduces the clearance of the magnetic heads above the disk surface to a few nanometers. Further, such a small clearance distance sometimes causes wear of the diamond like carbon (DLC) overcoat on the slider surface at the head–disk interface (HDI) owing to contact with the disk surface. The wear mechanisms of the DLC overcoat are considered to be either mechanical wear or tribochemical wear (oxidation of carbon) [1]. Recently, a helium-filled HDD was developed to improve the storage capacity and power consumption of HDDs. In the helium-filled HDD, tribochemical wear does not occur because there is no oxygen in the HDD. In addition, there is no humidity (water vapor), which was found to affect wear at the HDI [2]. Therefore, it is important to understand the effect of humidity and an oxygen-free inert gas environment on slider wear.

Numerical Investigation of Bouncing Vibrations of a Partial Contact Slider

2007 ◽  
Author(s):  
Du Chen ◽  
David D. Bogy
Keyword(s):  
Hard Disk Drives ◽  
Disk Surface ◽  
Air Bearing ◽  
Nonlinear Dynamic Model ◽  
Frequency Spectra ◽  
Disk Interface ◽  
Partial Contact ◽  
Adhesion Contact ◽  
Contact Situation ◽  
Contact Slider

A nonlinear dynamic model is developed to analyze the bouncing vibration of a partial contact air bearing slider, which is designed for the areal recording density in hard disk drives of 1 Tbit/in2 or even higher. In this model the air bearing with contact is modeled using the generalized Reynolds equation modified with the Fukui-Kaneko slip correction and a new second order slip correction for the contact situation [1]. The adhesion, contact and friction between the slider and the disk are also considered in the model. It is found that the disk surface roughness, which moves into the head disk interface (HDI) as the disk rotates, excites the bouncing vibrations of the partial contact slider. The frequency spectra of the slider’s bouncing vibration have high frequency components that correspond to the slider-disk contact.

Numerical Investigation of Thermal Effects on a HAMR Head-Disk Interface

2014 ◽  
Author(s):  
Kyaw Sett Myo ◽  
Weidong Zhou ◽  
Xiaoyang Huang ◽  
Shengkai Yu
Keyword(s):  
Temperature Field ◽  
Laser Beam ◽  
Numerical Investigation ◽  
Thermal Effects ◽  
Hard Disk ◽  
Disk Surface ◽  
Recording Media ◽  
Head Disk Interface ◽  
Disk Interface ◽  
High Density Recording

Heat-assisted magnetic recording (HAMR) is one of prospective high density recording technologies in current hard disk industry. It requires heating a spot on the recording media with the laser beam to overcome the superpara-magnetic limit. The heat produced by laser beam causes the temperature field on the hard disk surface to be highly non-uniform, which may lead to unexpectedly severe lubricant loss, or even the failure of the whole HAMR system. In the meantime, the heat loss caused by the optical delivery system may cause unwanted thermal protrusion on the slider body, which may affect slider’s flying stability in the end.

Simulation of Contact Behavior of the Thin Film of Hard Disk at Head/Disk Interface

2011 ◽  
Vol 287-290 ◽  
pp. 2339-2342
Author(s):  
Hong Rui Ao ◽  
Deng Pan ◽  
Hong Yuan Jiang
Keyword(s):  
Thin Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Hertzian Contact ◽  
Von Mises Stress ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Slider Motion ◽  
Von Mises ◽  
Layered Thin Film

The contact at head/disk interface in hard disk drives subject to an external shock has been studied using the finite element method. A rigid cylinder moving over a two-layered thin film was implemented to simulate the contact between the recording slider and the disk. The effects of different friction coefficients on the von Mises stress of two-layered thin film were investigated. The relation between pressed depth and width of deformation has been obtained. Results show that the amplitude decreases with increase of friction coefficient while the period of slider motion is diminution. In addition, the stress distribution fits Hertzian contact theory.

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