Browse Prior Art Database

Apparatus and Technique for 3D Microscopy and Profilometery of Magnetic Recording Hard Disks using a Flying Slider

IP.com Disclosure Number: IPCOM000111965D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 4 page(s) / 101K

Publishing Venue

IBM

Related People

Singh, GP: AUTHOR [+2]

Abstract

In this disclosure we describe an invention that allows in-situ profiling of a magnetic hard disk by sensitive measurement of electrical capacitance between a specially prepared conducting pad on the airbearing slider and the magnetic disk. We used IBM 3380 typesliders. The conducting pad is imbedded in sputtered alumina at the trailing end of the slider. Fig. 1 shows a picture of this sensor pad on the air bearing surface of the slider. These pads are made using techniques commonly employed for fabrication of thin film magnetic heads [1]. The pads used by us had an area of 15&mu.m X 20&mu.m. The capacitance was measured using the preamplifier from RCA VideoDisc player [2,3,4]. This amplifier can detect capacitance changes as small as 100 attofarads with a bandwidth of 1 MHz.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Apparatus and Technique for 3D Microscopy and Profilometery of Magnetic
Recording Hard Disks using a Flying Slider

      In this disclosure we describe an invention that allows in-situ
profiling of a magnetic hard disk by sensitive measurement of
electrical capacitance between a specially prepared conducting pad on
the airbearing slider and the magnetic disk.  We used IBM 3380
typesliders.  The conducting pad is imbedded in sputtered alumina at
the trailing end of the slider.  Fig. 1 shows a picture of this
sensor pad on the air bearing surface of the slider.  These pads are
made using techniques commonly employed for fabrication of thin film
magnetic heads [1].  The pads used by us had an area of 15&mu.m X
20&mu.m.  The capacitance was measured using the preamplifier from
RCA VideoDisc player [2,3,4].  This amplifier can detect capacitance
changes as small as 100 attofarads with a bandwidth of 1 MHz.  The
capacitance images are acquired when the disk is spinning on a
teststand and the disk surface is scanned by moving the slider in the
radial direction.  These images can then be converted to gray scale
images using computer based graphical techniques.  In this mode the
device produces microscope like images of the disk surface.  Since
the slider is flying on the disk, the technique is essentially
non-contact and non-destructive to the disk.

      Fig. 2 shows two capacitance microscope images of the same
region of a particulate disk.  The upper image is acquired at a disk
speed of 45 m/sec and...