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Lapping Guide Design for a Thin Film Magnetic Recording Head

IP.com Disclosure Number: IPCOM000120973D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 91K

Publishing Venue

IBM

Related People

Denison, EV: AUTHOR [+4]

Abstract

In the design of a thin film magnetic recording head, it is desirable to have the read stripe height and write throat height to be as short as possible to maximize head performance. Shorter heights require that the manufacturing tolerance of these heights is also minimized. One method of accomplishing this is the use of a thin film resistive lapping guide, commonly known as a Finish Lap Guide (FLG), which provides an electrical resistance monitor whose resistance increases as the stripe and throat height decrease during the lapping process. However, knowing at what resistance to stop lapping the FLG to result in a certain stripe and throat height is critical.

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Lapping Guide Design for a Thin Film Magnetic Recording Head

      In the design of a thin film magnetic recording head, it
is desirable to have the read stripe height and write throat height
to be as short as possible to maximize head performance.  Shorter
heights require that the manufacturing tolerance of these heights is
also minimized.  One method of accomplishing this is the use of a
thin film resistive lapping guide, commonly known as a Finish Lap
Guide (FLG), which provides an electrical resistance monitor whose
resistance increases as the stripe and throat height decrease during
the lapping process.  However, knowing at what resistance to stop
lapping the FLG to result in a certain stripe and throat height is
critical.

      One known solution requires the formation of a lapping guide
geometry having leads, or legs, and a resistive element, or lap
stripe.  Knowing the height and resistance of the lap stripe before
lapping, and the desired lap stripe height after lapping, the lapping
resistance target can be calculated from a simple ratio.  However, in
order to find the resistance of the lap stripe before lapping, the
leg resistance must be known to a high degree of accuracy, and is
dependant upon the leg area, resistivity of leg material, and
thickness of the leg material, all of which parameters vary as a
function of processing conditions.  Errors in obtaining the values of
these parameters contribute significantly to the error in calculating
the leg resistance, hence, in obtaining an accurate lapping target
resistance.  Additional errors exist in assumptions made regarding
constant current density throughout all of the resistive areas of the
legs and the lap stripe, which are not strictly true.  Such errors
described are intolerable as nominal stripe heights become shorter.

      Therefore, the problem to be solved is obtaining the target lap
stripe resistance without introducing the errors previously
described....