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In-Situ Measurement of Bump Height in the Landing Zone

IP.com Disclosure Number: IPCOM000118826D
Original Publication Date: 1997-Jul-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Lee, CK: AUTHOR [+2]

Abstract

The bump heights in the landing zone on the surface of a magnetic disk are measured in-situ by using the magnetic playback signal from the read head. Knowledge of the bump heights is one of the indicators necessary to ensure that a given head-disk interface will operate reliably over the intended life of a disk drive.

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In-Situ Measurement of Bump Height in the Landing Zone

      The bump heights in the landing zone on the surface of a
magnetic disk are measured in-situ by using the magnetic playback
signal from the read head.  Knowledge of the bump heights is one of
the indicators necessary to ensure that a given head-disk interface
will operate reliably over the intended life of a disk drive.

      In modern hard disk drives, the disk surfaces are highly
polished so that the recording and playback elements can be as close
as possible to the magnetic storage medium.  The elements are
attached to a slider which floats above a disk surface with a spacing
of a few hundred Angstroms.  The close proximity is necessary to
achieve the high storage capacities for today's disk drives.  If a
slider were  to stop and rest on the disk surface, very large
stiction forces would  result which could not be overcome by the
motor torque.  This would render the hard drive useless and all of
the data stored on the disks in the drive would be lost.

      To eliminate the stiction problem, the polished disks contain a
landing zone for a slider that has a roughened surface.  A popular
method of achieving roughness is to create periodic bumps on the
disks by using a pulsed laser.  Due to tolerances in disk geometry,
material, and laser output, there is some variation in the actual
bump heights.  Disks which contain bumps with lower heights can cause
stiction.  Disks with bumps that are t...