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Method for Thermal Erasure Detecting and Analysis of Thin Film Hard Disks and Sliders

IP.com Disclosure Number: IPCOM000010437D
Original Publication Date: 2002-Dec-02
Included in the Prior Art Database: 2002-Dec-02
Document File: 2 page(s) / 214K

Publishing Venue

IBM

Abstract

This method is capable of evaluating thermal erasure properties of disks and head sliders for both longitudinal and perpendicular magnetic recording. It also enables us to study the details of head disk interaction, such as slider disk contact points and slider vibration modes responsible for the thermal erasure. This is difficulty to be obtained by other means.

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  Method for Thermal Erasure Detecting and Analysis of Thin Film Hard Disks and Sliders

Thermal erasure of written data on disks is one of the major file failure mechanisms, especially for disks using glass substrates due to their poor thermal conductivity (0.76 W/mC compared to 127 W/mC for NiP/AlMg substrates). Most of the thermal erasure events are due to head disk contact. There are no controllable and quantitative methods, however, available to evaluate disk and slider thermal erasure properties. In this invention we developed a method to fulfill such a function. The head disk contact is induced by lowering the pressure of a vacuum chamber where a spin-stand test sits. The pressure at which the head starts contacting the disk is determined by the appearance of the thermal contact (TC) signal of the MR/GMR read sensor. The head disk contact at this pressure is gentle enough to not produce any disk and slider wear and topographic changes but strong enough to rise the magnetic film's temperature beyond its Curie temperature and thus thermally erase the pre-written data.

The heat that rises the magnetic film temperature has two major sources, namely the frictional heat due to the head disk contact and the Joule heat via either surface or bulk conduction form the MR/GMR sensor to the disk. From the characteristics of TC signal wave forms the temperature rise mechanism can be determined. After a certain time of head disk contact the vacuum chamber is pumped up to ro...