Perpendicular Magnetic Recording Head Side Shield Corner Design

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Solution Overview

Problem

In perpendicular magnetic recording heads with narrowed track widths, side fringing is exacerbated by acute corners on the side shield layers, leading to unintentional recording and erasing due to magnetic field concentration.

Innovation Solution

The formation of side shield layers with angles of 90° or greater at their corners, achieved by extending the side end face from the front end face in a linear or curved manner, prevents magnetic field concentration and leakage fluxes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If rectangular side shield layers are formed by photolithography, then the manufacturing process is simple, but optical proximity effect causes corner rounding and acute corners to be exposed at the medium-opposing surface

Engineering Contradiction:

Improveside shield layer formation processVSAvoidcorner shape accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The side end face of the side shield layer is designed with a curved surface (circular arc) instead of a straight line, so that when the front end face has an acute corner, the side end face curvature ensures the corner does not extend to the medium-opposing surface. This curvature design prevents the formation of exposed acute corners while maintaining manufacturing feasibility through standard photolithography processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Measurement precision

If the track width is narrowed to achieve higher recording density, then the recording precision is improved, but side fringing is exacerbated due to magnetic field concentration at acute corners

Engineering Contradiction:

Improverecording precisionVSAvoidside fringing

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The side shield layer is designed with non-uniform geometry: the front end face has an acute corner for precise field confinement, while the side end face has a curved surface that prevents corner exposure. This local differentiation allows the acute corner to concentrate the magnetic field for precise recording, while the curved side end face prevents side fringing by avoiding magnetic field concentration at exposed corners.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The acute corner at the front end face, which would normally cause harmful side fringing, is converted into a beneficial feature for precise field confinement. The harm is neutralized by designing the side end face with a curved surface that prevents the acute corner from extending to the medium-opposing surface, thus eliminating side fringing while maintaining the field-confinement advantage of the acute corner.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If acute corners are exposed at the medium-opposing surface, then the side shield layer structure is simple, but magnetic fields concentrate at the corners causing unintentional recording and erasing

Engineering Contradiction:

Improveside shield layer structureVSAvoidrecording reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The side end face is designed with a curved surface (circular arc) instead of a straight line, which prevents the formation of exposed acute corners at the medium-opposing surface. This curvature ensures that even when the front end face has an acute corner, the side end face geometry prevents the corner from reaching the medium-opposing surface, thereby eliminating magnetic field concentration and preventing unintentional recording and erasing.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design effectively reduces unintentional recording and erasing by dispersing magnetic fields over a wider area, enhancing recording characteristics for higher densities.

Implementation Method 1

a coil layer inducing a recording magnetic field between the main magnetic pole layer and return yoke layer upon energization

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

lateral magnetic fluxes leaking from both side faces in the track width direction of the magnetic pole part are absorbed by the pair of side shield layers

Methodology Applied

Scientific EffectMagnetic flux absorption: Absorption (physical)

Data Source

PatentUS8054581B2Perpendicular magnetic recording head

Publication Date: 2011.11.08 TDK CORP

AI summary

To provide a perpendicular magnetic recording head which can prevent unintentional recording and erasing from occurring on recording media.In a perpendicular magnetic recording head comprising a pair of side shield layers made of a soft magnetic material on both sides in a track width direction of a magnetic pole part of a main magnetic pole layer, the pair of side shield layers have a front end face exposed at a medium-opposing surface and a side end face extending from one end part of the front end face remote from the magnetic pole part in the track width direction to the deeper side in a height direction, while the front end face and the side end face form an angle of 90° or greater therebetween.