Smear Growth of Siloxane Outgas at Laser Heating

2017 ◽  
Author(s):  
Hiroshi Tani ◽  
Norio Tagawa ◽  
Renguo Lu ◽  
Shinji Koganezawa
Keyword(s):  
Laser Heating ◽  
Thermal Evaporation ◽  
Laser Light ◽  
Hard Disk Drives ◽  
Areal Density ◽  
Disk Surface ◽  
Disk Drives ◽  
Flash Temperature ◽  
Magnetic Head ◽  
Magnetic Disk

Siloxane outgas is well known to cause smears on magnetic head sliders. Siloxane outgas is vaporized from certain components in hard disk drives (HDDs), that adsorbs on the magnetic disk surfaces, and SiO2 that is denatured from siloxane by flash temperature at a slider and disk contact gets accumulated on the slider surface. On the other hand, heat assisted magnetic recording (HAMR) is being developed to improve areal density. In HAMR, a laser light heats the magnetic disk surface to 400–500 K. Siloxane adsorbed on a disk surface easily gets desorbed from the disk surface owing to thermal evaporation and dissociation by laser heating. In this study, we have studied smear growth from siloxane outgas on laser heating. We observe that the siloxane adsorbed on the disk surface grew on the glass surface above the disk surface at the laser heating spot.

The Simulation of Laser Cleaning of Magnetic Head with Different Temporal Pulses

2015 ◽  
Vol 1101 ◽  
pp. 446-452 ◽  
Author(s):  
Narongpun Rungcharoen ◽  
Mongkol Wannapapra ◽  
Wanchai Pijitrojana
Keyword(s):  
Hard Disk Drives ◽  
Disk Surface ◽  
Laser Cleaning ◽  
User Requirements ◽  
Particle Removal ◽  
Disk Drives ◽  
Magnetic Head ◽  
Small Particles ◽  
Fly Height ◽  
Non Destructive

Nowadays, hard disk drives (HDD) technology are being developed continuously in order to increase the capacity, and reduce the size of HDD to meet user requirements. To increase the capacity which is equivalent to increasing read/write ability, the flying clearance must be reduced. Current new HDD models show that the fly height is lower than 0.3 μm. If the height of a particle or contamination is higher than 0.3 μm, the magnetic head will scratch the magnetic disk surface. However the process of cleaning in the HDD industry cannot remove particles with size smaller than 0.3 μm [1]. Therefore laser cleaning is selected first because this method can remove small particles [2]. and it does not damage the magnetic head. This research compares the range of temperature needed for cleaning the magnetic head between two types of heat source’s profile. The technique used is the heat transfer by finite element: FEM[3]. This technique provides an important factor of the laser cleaning method that increases the efficiency of particle removal. It is also a non-destructive method for cleaning the surface of the magnetic head slider.

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.

Reduction of Head Wear on Thin-Film Magnetic Disks

2002 ◽  
Author(s):  
Youich Kawakubo ◽  
Shunichi Miyazawa ◽  
Kenjirou Nagata ◽  
Shinichi Kobatake
Keyword(s):  
Thin Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Surface ◽  
Disk Drives ◽  
Magnetic Disks ◽  
Surface Flattening ◽  
Magnetic Disk ◽  
Pin On Disk ◽  
Wear Tests

It is necessary to reduce head wear to develop future hard disk drives. For this purpose, we have been studying transparent pin-on-disk wear tests on thin-film magnetic disks. We reported that pin wear on thin-film magnetic disk showed running-in effects. The reason of the running-in was considered to be a result of disk surface flattening. This means that if we could introduce an efficient burnishing technique, we could reduce head wear in operation. We then introduced a burnishing technique using a hemispherical diamond slider and compared pin wear on disk surfaces with and without burnishing. The results showed that the pin wear was reduced by the introduction of the burnishing technique. We consider that burnishing with hard round slider is another way of reducing head wear on future disk surfaces.

Improvement of the Static and Dynamic Characteristics of Magnetic Head Sliders by Optimum Design

1999 ◽  
Vol 122 (1) ◽  
pp. 280-287 ◽  
Author(s):  
Hiromu Hashimoto ◽  
Yasuhisa Hattori
Keyword(s):  
Objective Function ◽  
Optimum Design ◽  
Amplitude Ratio ◽  
Optimization Technique ◽  
Hard Disk Drives ◽  
Maximum Amplitude ◽  
Disk Surface ◽  
Operating Conditions ◽  
Magnetic Head ◽  
Design Variables

The aim of this paper is to develop a general methodology for the optimum design of magnetic head sliders in improving the spacing characteristics between a slider and disk surface under static and dynamic operating conditions of hard disk drives and to present an application of the methodology to the IBM 3380-type slider design. To generate the optimal design variables, the objective function is defined as the weighted sum of the minimum spacing, the maximum difference in the spacing due to variation of the radial location of the head, and the maximum amplitude ratio of the slider motion. Slider rail width, taper length, taper angle, suspension position, and preload are selected as the design variables. Before the optimization of the head, the effects of these five design variables on the objective function are examined by a parametric study, and then the optimum design variables are determined by applying the hybrid optimization technique, combining the direct search method and successive quadratic programming. From the obtained results, the effectiveness of optimum design on the spacing characteristics of magnetic heads is clarified. [S0742-4787(00)03701-2]

Depletion of Moleculary Thin Lubricant Under Flying Head in Hard Disk Drives

2007 ◽  
Author(s):  
Kenji Yanagisawa ◽  
Youichi Kawakubo ◽  
Masato Yoshino
Keyword(s):  
Thin Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Lubricant Film ◽  
Simulation Program ◽  
Disk Drives ◽  
Lubricant Thickness ◽  
Magnetic Disk ◽  
Lubricant Depletion ◽  
Lubricant Films

In Hard Disk Drives, lubricants are very important materials to reduce head and disk wear. Therefore, it is necessary to know the lubricant depletion under flying heads. Lubricant depletion due to flying heads has been studied experimentally. We developed simulation program to calculate numerically the change in lubricant thickness under a flying head on a thin-film magnetic disk from 10nm thick lubricant film. In recent HDDs, the lubricants thickness has become molecularly thin and polar lubricants have been used. In this paper, we took account of thickness-dependent lubricants diffusion and viscosity in our simulations to calculate a 1.2 nm thick polar lubricant film used in recent HDDs. The simulated results considering the thickness-dependent diffusion and viscosity showed that depletion was small in molecularly thin lubricant films. We considered it necessary to include thickness-dependent diffusion and viscosity in lubricant depletion simulation.

Effects of Molecularly Thin Liquid Lubricant Film Materials on Slider Hysteresis Instability in Hard Disk Drives

2007 ◽  
Author(s):  
Norio Tagawa ◽  
Daisuke Tanaka ◽  
Atsunobu Mori
Keyword(s):  
Hard Disk Drives ◽  
Disk Surface ◽  
Intermolecular Forces ◽  
Experimental Results ◽  
Disk Drives ◽  
Friction Forces ◽  
Liquid Lubricant ◽  
Pressure Test ◽  
Lower Mobility ◽  
The Difference

In this study, the difference in the touchdown and takeoff pressures was monitored by using three types of lubricant materials, namely, Zdol2000, Ztetraol2000 and A20H2000 by using the pump down pressure test. The results indicated that the touchdown pressures depended on the lubricant materials; it was greatest for Ztetraol2000 and smallest for A20H2000. The takeoff pressure was greater for a lubricant with lower mobility. Considering these experimental results, it was suggested that the variation in the touchdown pressure is due to a variation in the intermolecular forces, taking into account the lubricant pickup by a slider. Further, it was suggested that the variation in the takeoff pressure is caused by a variation in the friction forces between the slider and disk surface.

Design and Dynamics of Flying Height Control Slider With Piezoelectric Nanoactuator in Hard Disk Drives

2006 ◽  
Vol 129 (1) ◽  
pp. 161-170 ◽  
Author(s):  
Jia-Yang Juang ◽  
David B. Bogy ◽  
C. Singh Bhatia
Keyword(s):  
Numerical Study ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Areal Density ◽  
Flying Height ◽  
Air Bearing ◽  
Disk Drives ◽  
Adhesion Forces ◽  
Surface Design ◽  
Ultrahigh Density

To achieve the areal density goal in hard disk drives of 1Tbit∕in.2 the minimum physical spacing or flying height (FH) between the read/write element and disk must be reduced to ∼2nm. A brief review of several FH adjustment schemes is first presented and discussed. Previous research showed that the actuation efficiency (defined as the ratio of the FH reduction to the stroke) was low due to the significant air bearing coupling. In this paper, an air bearing surface design, Slider B, for a FH control slider with a piezoelectric nanoactuator is proposed to achieve virtually 100% efficiency and to increase dynamics stability by minimizing the nanoscale adhesion forces. A numerical study was conducted to investigate both the static and dynamic performances of the Slider B, such as uniformity of gap FH with near-zero roll over the entire disk, ultrahigh roll stiffness and damping, low nanoscale adhesion forces, uniform FH track-seeking motion, dynamic load/unload, and FH modulation. Slider B was found to exhibit an overall enhancement in performance, stability, and reliability in ultrahigh density magnetic recording.

Stochastic Evaluation of Magnetic Head Wears in Hard Disk Drives

2014 ◽  
Vol 50 (5) ◽  
pp. 1-7 ◽  
Author(s):  
Yu Wang ◽  
Zhi-Sheng Ye ◽  
Kwok-Leung Tsui
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Magnetic Head
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