Flyability Failures Due to Organic Siloxanes at the Head/Disk Interface

1999 ◽  
Vol 122 (2) ◽  
pp. 444-449 ◽  
Author(s):  
Vedantham Raman ◽  
Donald Gillis ◽  
Reinhard Wolter
Keyword(s):  
Adhesive Tape ◽  
Head Disk Interface ◽  
Recording Industry ◽  
Interface Failure ◽  
Disk Interface ◽  
Release Liner ◽  
Volatile Materials ◽  
Full Body

With the trend toward lower flying heights and increasing storage capacity in the magnetic recording industry, the role of contamination and methods to counteract its deleterious effects are expected to become important. One area where the role of contaminants is expected to increasingly affect reliability is long term flyability. This is because volatile and semi-volatile materials in the drive can alter the flying characteristics of the slider during operation because of chemistry at the interface. In this paper, we describe the flyability performance of a head-disk interface system using full body capacitance measurements as a monitor of interface reliability. The principal features observed in flyability tests employing two sources of siloxanes, a model organic compound octamethylcyclotetrasiloxane as well as outgassing from an exposed adhesive tape with a release liner, are described. The deleterious effects of siloxane outgassing that lead to changes in the flying characteristics of the slider and subsequent interface failure are described for disks lubricated with Fomblin Z-dol. Chemical identification of the accumulated material on the slider following flyability testing is described. Strikingly different performance is observed for disks lubricated with the cyclic phosphazene X-1P which shows significantly improved flyability performance. Possible mechanisms that lead to the formation of silica at the head-disk interface for Z-dol based disks and reasons for their absence for an X-1P interface are discussed. [S0742-4787(00)01202-9]

Head-Disk Interface Issues for Near Contact Recording

2001 ◽  
Author(s):  
R. H. Wang ◽  
V. Raman ◽  
U. V. Nayak
Keyword(s):  
Ambient Pressure ◽  
Disk Drive ◽  
Flying Height ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Magnetic Spacing ◽  
Wear And Corrosion ◽  
Disk Lubricant ◽  
Contact Recording

Abstract As the magnetic recording density increases towards hundreds of Gb/in2, both the magnetic spacing and head-disk clearance decrease to < 10 nm. By one estimate, the magnetic spacing for 1 Tb/in2 is about 6 nm and the read width is ∼ 30 nm. There are at least two different approaches to achieving this. The first one is an extension of the traditional flying interface and the second is contact recording. In the former case one needs to be concerned about maintaining adequate clearance both at sea level and at higher elevation whereas in the latter case the wear and corrosion of the heads and disks may pose major challenges. In the flying regime, an accelerated test to assess the relative integrity of the head-disk interface is described here. This is accomplished by monitoring the acoustic emission, capacitance or friction between the head and the disk as the ambient pressure is reduced. The pressure at which an abrupt change in the above signals takes place is called take-off pressure (TOP). This is also known as altitude avalanche measurement. With this method it is possible to compare different disk and head designs at the full velocity of the slider. We present results correlating the TOP with disk roughness and the influence of disk lubricant. An example of how head-disk interference takes place in a disk drive will be given for an experimental 10 nm flying slider. The effects of radial flying height profile, take-off height of the disk, and the disk curvature on mechanical spacing are presented. The results of changes occurring on the air bearing surface and the disks after long term flyability test are discussed.

Tribological Characteristics of Liquid Lubricant on Magnetic Disks Treated by Far-UV Radiation

1993 ◽  
Vol 115 (3) ◽  
pp. 400-405 ◽  
Author(s):  
Hong Tian ◽  
Takeo Matsudaira
Keyword(s):  
Slip Model ◽  
Head Disk Interface ◽  
Rotating Disks ◽  
Magnetic Disks ◽  
Disk Interface ◽  
Liquid Lubricant ◽  
Long Period ◽  
Irradiation Treatment ◽  
Temperature Environment

In this paper, we have shown that a perfluoropolyether lubricant after far-UV irradiation treatment proposed by Saperstein and Lin (1990) was strongly bonded to disk surfaces without depletion from disks rotating at 6000 rpm in a 50°C temperature environment. Nonbonded lubricant (mobile lubricant) on disk surfaces or on the top of the UV-fixed lubricant was easily depleted from rotating disks. Depletion data of the mobile lubricant agreed well with predictions of an inter-slip model. It has been demonstrated experimentally that the mobile lubricant on disk surfaces was simply displaced from the contact or the sliding regions. After a long period of head contact, the lubricant was built up at the head/disk interface due to migration of the mobile lubricant around the contact regions. By contrast, no such build-up was observed for disks with the UV-fixed lubricant. Consequently, long-term stiction was observed for disks with only mobile lubricant, while no stiction was observed for disks with the UV-fixed lubricant. The UV-treated disks also adsorbed less water at high relative humidities compared with the nontreated disks.

The Role of Relative Humidity, Surface Roughness and Liquid Build-Up on Static Friction Behavior of the Head/Disk Interface

1993 ◽  
Vol 115 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Hong Tian ◽  
Takeo Matsudaira
Keyword(s):  
Surface Roughness ◽  
Relative Humidity ◽  
Static Friction ◽  
Height Distribution ◽  
Head Disk Interface ◽  
Friction Behavior ◽  
Friction Forces ◽  
Disk Interface ◽  
Percent Relative Humidity

Stiction at the head/disk interface has become one of the major concerns as smoother surfaces are required to achieve lower flying heights of magnetic heads over magnetic disks. In this paper, static friction forces on three types of disk samples with different surface roughness values were measured at various relative humidities. It was found that static friction coefficients were well correlated with total thickness of liquid (lubricant and adsorbed water) at the head/disk interface. The experimental data also agreed fairly well with the calculated values based on a proposed stiction model. It is implied in the stiction model that the bearing ratio or the shape of asperity height distribution, especially the part of high asperities, determines the stiction force. Moreover, long-term stiction was investigated on the unlubricated disk surfaces at 80 percent relative humidity and on the lubricated disks at 5 percent relative humidity to separate the effects of water build-up and lubricant build-up at the head/disk interface. It appears that long-term stiction occurs only when enough mobile lubricant is present and the thickness of liquid at the head/disk interface is close to a critical thickness value which is related to surface roughness values.

Track seeking, head-disk spacing variation and head-disk interface failure

1997 ◽  
Vol 33 (5) ◽  
pp. 3136-3138 ◽  
Author(s):  
Bo Liu ◽  
Qisuo Chen ◽  
Zhimin Yuan ◽  
Gang Sheng
Keyword(s):  
Head Disk Interface ◽  
Interface Failure ◽  
Disk Interface ◽  
Spacing Variation ◽  
Disk Spacing

Study of clock head/disk interface failure mechanism in servo-writing process

1998 ◽  
Vol 34 (4) ◽  
pp. 1723-1725 ◽  
Author(s):  
Bo Liu ◽  
Gang Sheng ◽  
Qisuo Chen ◽  
Qingfang Leng ◽  
C.T. Yeo ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Writing Process ◽  
Head Disk Interface ◽  
Interface Failure ◽  
Disk Interface
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