Browse Prior Art Database

Thermal Asperities Detection and Avalanche Measurement on Component Level for Disks

IP.com Disclosure Number: IPCOM000118434D
Original Publication Date: 1997-Feb-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Heinrich, V: AUTHOR [+2]

Abstract

Disclosed is a method for characterizing of a Thermal Asperities (TA) behavior of a head disk interface. Today, disk surfaces are textured to avoid stiction and to improve the orientation ratio of the magnetic coating. To get higher linear bit densities, the flying height has to be reduced. By using Magnetoresistive (MR) heads, the MR stripe can touch particles and texture protrusions. This causes spikes in the read back signal called thermal asperities and leads to read errors. To characterize the TA behavior of a head disk interface, an altitude test is performed on the Disk Enclosure (DE) level. The air pressure is reduced in a vacuum chamber and, consequently, the flying height is decreased. If the disk has surface irregularities, the MR heads detect TAs.

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Thermal Asperities Detection and Avalanche Measurement on Component
Level for Disks

      Disclosed is a method for characterizing of a Thermal
Asperities (TA) behavior of a head disk interface.  Today, disk
surfaces are textured to avoid stiction and to improve the
orientation ratio of  the magnetic coating.  To get higher linear bit
densities, the flying height has to be reduced.  By using
Magnetoresistive (MR) heads, the MR  stripe can touch particles and
texture protrusions.  This causes spikes  in the read back signal
called thermal asperities and leads to read errors.  To characterize
the TA behavior of a head disk interface, an altitude test is
performed on the Disk Enclosure (DE) level.  The air pressure is
reduced in a vacuum chamber and, consequently, the flying height is
decreased.  If the disk has surface irregularities, the MR heads
detect TAs.  There is no equivalent test on a component level
available to characterize topographical defects, like texture
protrusion, sputter spittings and mechanical damages.

The characterization can be done on a normal spin stand on component
level:
  1.  Select heads which are TA sensitive.  These are heads which
       are linear lapped with less pole tip recession and less
       crown.  These heads should have an Air Bearing Surface (ABS)
       profile such that the flying height can be influenced by the
       relative velocity between the disk and the head.  From these
     ...