Variable Side Shield Gap Magnetic Recording Head

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Solution Overview

Problem

Current hard disk drive write heads with trailing shields suffer from poor cross-track field gradients, leading to adjacent track interference and erasure due to large stray fields, and existing solutions face design and fabrication challenges.

Innovation Solution

The implementation of magnetic recording heads with variable side shield gaps, where the trailing edge of a side shield is spaced further in the cross-track direction than the leading edge, improving cross-track field gradients and allowing for easier fabrication of rectangular cross-sectional write poles using mill & lap or damascene processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If trailing shields are used in write heads, then recording density can be increased, but cross-track field gradients deteriorate leading to adjacent track interference

Engineering Contradiction:

Improverecording densityVSAvoidcross-track field gradients

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The side shields are positioned at specific locations (sides of the write pole) rather than uniformly distributed, creating localized field control zones. This allows the magnetic field to be shaped locally at the pole tips to improve cross-track gradients while maintaining overall recording density benefits of the trailing shield configuration.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Side shields are introduced as intermediary magnetic structures between the write pole and adjacent tracks. These side shields act as mediators that redirect and contain the magnetic flux, preventing it from spreading into adjacent tracks while allowing the main write field to penetrate the recording medium effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If wrap-around shields are added to reduce adjacent track interference, then ATI is reduced, but device complexity increases

Engineering Contradiction:

Improveadjacent track interferenceVSAvoidshield structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The side shields are extracted as separate, discrete components from the write head assembly rather than being integrated as complex wrap-around structures. This extraction allows for simpler fabrication where side shields can be independently formed and positioned, reducing overall device complexity while maintaining ATI reduction benefits.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The shield structure is segmented into distinct components: the main trailing shield and separate side shields. This segmentation allows each component to be optimized independently for its specific function, simplifying the overall design and fabrication process compared to a monolithic wrap-around shield structure.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If conventional side shield configurations are used, then ATI is reduced, but fabrication difficulty increases

Engineering Contradiction:

Improveadjacent track interferenceVSAvoidfabrication difficulty

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

Shadowing structures are formed preliminarily during the fabrication process to define the side shield geometry. These shadowing structures are created before the side shields themselves, allowing for precise positioning and shape control of the side shields through subsequent deposition processes, thereby simplifying the overall fabrication sequence.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Complex mechanical alignment and positioning operations are replaced by self-aligning fabrication processes. The side shields are deposited conformally on the write pole, and shadowing structures automatically define the correct positions and shapes, eliminating the need for precise mechanical positioning steps that would increase fabrication difficulty.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 configuration enhances cross-track field gradients, reduces adjacent track interference, and simplifies the manufacturing process by allowing the use of more easily fabricated write poles with improved performance and compatibility with beveled heads.

Implementation Method 1

The shadowing structures are configured to shadow a lower portion of the write pole such that the deposited side wall gap layers are thinner adjacent the lower portion and thicker adjacent a region above the lower portion

Methodology Applied

Scientific EffectShadowing: Shadow

Data Source

PatentUS9251813B1Method of making a magnetic recording head

Publication Date: 2016.02.02 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

A magnetic recording head comprises a write pole including a throat region with a leading edge, a trailing edge opposite the leading edge, and first and second side edges opposite one another. The magnetic recording head further comprises a first side wall gap layer disposed alongside the first side edge of the throat region, and a second side wall gap layer disposed alongside the second side edge of the throat region. Each of the first and second side wall gap layers has a first width at the leading edge of the throat region smaller than a second width at the trailing edge of the throat region.