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Sliders with Well Defined Undulation Patterns on the ABS for Improved Stiction and Flyability

IP.com Disclosure Number: IPCOM000121666D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 109K

Publishing Venue

IBM

Related People

O'Sullivan, T: AUTHOR [+3]

Abstract

Described here is a new class slider Air Bearing Surface (ABS) with well-defined undulation patterns that can result in reduced contact area with the disk, and hence reduced stiction. Additional advantages of such sliders are: (i) little problem with wear is expected since the undulations are precisely controlled and smooth; (ii) well-de signed undulation patterns can result in tailored ABS stiffness, hence an additional handle on flight height, pitch angel, or gram-load; (iii) such undulations can be batch fabricated by three-dimensional lithography technique on a wafer.

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Sliders with Well Defined Undulation Patterns on the ABS for Improved
Stiction and Flyability

      Described here is a new class slider Air Bearing Surface
(ABS) with well-defined undulation patterns that can result in
reduced contact area with the disk, and hence reduced stiction.
Additional advantages of such sliders are: (i) little problem with
wear is expected since the undulations are precisely controlled and
smooth; (ii) well-de signed undulation patterns can result in
tailored ABS stiffness, hence an additional handle on flight height,
pitch angel, or gram-load; (iii) such undulations can be batch
fabricated by three-dimensional lithography technique on a wafer.

      "Undulation" here means roughness with well-defined and
controlled smoothness and directionality.  It is already known [1,2]
that the air bearing lifting force at the ABS depends not only on the
magnitude of the roughness, but also on the "directionality" of the
roughness.  The directionality of a surface can be characterized by a
parameter g defined as follows.  If ACF (0.5) is the length at which
the auto-correlation function of a profile reduces to 50% of its
initial value, then g is the ratio of ACF (0.5) in the x and y
directions [1] and can be physically visualized as the
length-to-width ratio of a representative asperity.  Special cases
are g = 0, when the roughness is all transverse, and g = infinity,
where the roughness is all longitudinal and g = 1 basically
corresponds to roughness aligned at 45 degrees.  For the case of an
ABS with long and narrow rails, the airflow under the rails is
dominated by side leakage.  Cases corresponding to g = 0, 1 and
infinity are schematically shown in Figs. 1(a), (b), and (c),
respectively.  These designs will result in air bearing lift force
for a constant flying velocity being smaller, equal, and larger than
the flat (non...