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.

Head Wear in Contact Recording Systems

2003 ◽  
Author(s):  
Youichi Kawakubo ◽  
Shinichi Kobatake ◽  
Shunichi Miyazawa ◽  
Shinichi Nakazawa
Keyword(s):  
Thin Film ◽  
Wear Debris ◽  
Hard Disk Drives ◽  
Disk Surface ◽  
Disk Drives ◽  
Magnetic Disks ◽  
Disk Lubricant ◽  
Pin On Disk ◽  
Contact Recording ◽  
Wear Tests

The possibility of disk failure, a common failure mode conventional HDDs, was studied in conditions supposed contact recording systems. For this purpose, transparent pin-on-disk wear tests were performed on thin-film magnetic disks with sliding load less than 5 mN. We found that visible wear scar did not appear on disk surfaces. Wear debris were found be buried on the disk surfaces. This showed that the reduction of head wear and vibration are two main problems to be solve for future hard disk drives. We then studied effects of disk lubricant and tape burnishing of disk surface on pin wear. The results showed the higher the molecular weight of lubricants, the lower the pin wear, and tape burnishing reduced pin wear.

Tribological Characteristics of Thin-Film Disks With and Without Mobile Lubricant

2009 ◽  
Author(s):  
Youichi Kawakubo ◽  
Takahiro Hayakawa ◽  
Yusuke Sugawara ◽  
Koji Ikeda ◽  
Osamu Kitamura
Keyword(s):  
Thin Film ◽  
Hard Disk Drives ◽  
Disk Surface ◽  
Tribological Characteristics ◽  
Disk Drives ◽  
Slow Speed ◽  
Force Increase ◽  
Low Load ◽  
Pin On Disk ◽  
Wear Tests

Lubricant on thin-film magnetic disks is divided into two parts. One is bonded lubricant that is fixed on disk surface and remains on disk surface after solvent rinsing. The other is mobile lubricant that can move on disk surface and is removed by solvent rinsing. It has been believed that mobile lubricant is imperative to design reliable hard disk drives. However, mobile lubricant would also be a cause of high friction between heads and disks. We started our studies on disks without mobile lubricant to find the possibility of disks with only bonded lubricant. In this paper, tribological characteristics of disks with and without mobile lubricant at the same lubricant thickness were compared using our transparent pin-on-disk wear tests. The results showed that pin wear was smaller on disks without mobile lubricant than those on disks with mobile lubricant in low load or slow speed conditions. The reason of this was considered to be the contact force increase by meniscus force due to lubricant bridge.

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.

Rupture and Reformation of Ultra-Thin Surface Films

2010 ◽  
Author(s):  
William W. F. Chong ◽  
Mircea Teodorescu ◽  
Homer Rahnejat
Keyword(s):  
Thin Film ◽  
Data Storage ◽  
Surface Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Surface Films ◽  
Disk Drives ◽  
Film Rupture ◽  
Near Surface ◽  
Ultra Thin Film

In lubricated contact conjunctions film ruptures close to the exit boundary. This significantly affects the load carrying capacity and can lead to direct surface interactions. Nano-scale films (several molecular diameters of the lubricant) are no exception, a fact that has been observed using ellipsometry studies for ultra-thin film conjunctions representative for high storage capacity hard disk drives. Immediately beyond the film rupture an area of cavitation occurs and the continuity of flow condition is breached. It has been shown that for molecularly smooth surfaces solvation effect becomes dominant. This means that the contact exit is subject to discrete drainage of lubricant and may be devoid of a sufficient lubricant for film reformation to occur. This can be a stumbling block in an increasing quest to increase the data storage density of hard disk drives. Wear can become a problem as well as non-uniformity of free surface film at the inlet meniscus. It has been noted that peaks of lubricant can gather in some places, a phenomenon referred to as lubricant mogul. These localized piles of lubricant can exceed the nominally aimed for lubricant film thickness necessary for a given data storage level. This paper carries out an in-depth prediction of ultra thin film lubricant behavior through the contact. Hydrodynamic as well as near surface effects and intermolecular interactions responsible for the supply, formation, cavitation and reformation of thin films in the slider-disk conjunction have been considered.

Transparent Pin Wear Test on Thin-Film Magnetic Disk

1995 ◽  
Vol 117 (2) ◽  
pp. 297-301 ◽  
Author(s):  
Youichi Kawakubo ◽  
Yotsuo Yahisa
Keyword(s):  
Thin Film ◽  
Wear Debris ◽  
Wear Test ◽  
Video Camera ◽  
Video Monitoring ◽  
Friction Measurement ◽  
Magnetic Disks ◽  
Bulk Hardness ◽  
Pin On Disk ◽  
Wear Tests

Pin-on-disk wear tests on thin-film magnetic disks were performed using transparent materials. Quartz glass (QG), transparent zirconia (TZ), sapphire (SA), and synthesized diamond (DI) were used as pin materials. In addition to friction, sliding condition and pin wear were continuously monitored with video camera. Simultaneous friction measurement and video monitoring showed that friction dropped when wear debris intruded between pin and disk surfaces. Pin wear, from the measured diameter of wear scar on spherical pins, increased in the order of DI, SA, QG, and TZ. This order of pin wear does not coincide with that of the pin bulk hardness. Disk lifetime increased in the order of TZ, QG, SA, and DI, and the smaller the pin wear, the longer the disk lifetime.

Compatibility of silicon planar heads with conventional thin film heads in hard disk drives

1992 ◽  
Vol 28 (5) ◽  
pp. 2124-2126 ◽  
Author(s):  
E. Autino ◽  
J.P. Lazzari ◽  
C. Pisella
Keyword(s):  
Thin Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives

Development of Multi-Layered Composite PZT Thin Films for Active Sliders in Hard Disk Drives

2002 ◽  
Author(s):  
Norio Tagawa ◽  
Ken-ichi Kitamura ◽  
Atsunobu Mori
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Sol Gel ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Layered Composite ◽  
The Novel ◽  
Disk Drives ◽  
Pzt Thin Films ◽  
Pzt Thin Film

This paper describes the development of novel PZT thin films for active sliders in hard disk drives. So far, it is common that single-layered thin films are used as micro-actuators for conventional PZT thin films such as sol-gel or sputtered thin films. In this study, however, the novel composite PZT thin films are developed. The feature is that sol-gel PZT thin film is deposited on sputtered PZT thin film fabricated on Pt/Ti bottom electrode. These multilayered composite PZT thin films are found to have the higher (111) preferred orientation as well as better P-E hysteresis loop characteristics than not only sol-gel PZT thin films but also sputtered PZT thin films. Furthermore, the piezoelectric strain constant d31 for the novel PZT thin films is identified to be 189 × 10−12m/V. This value is 2.0 times higher than that for conventional PZT thin films and it is found that the novel PZT thin films have good piezoelectric properties.

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