Magnetic Write Pole Assist Portion for Throat Height Control

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Solution Overview

Problem

Conventional magnetic recording apparatuses suffer from performance issues due to side shield tails developed during fabrication, which increase effective throat height and cause magnetic flux shunting, affecting recording accuracy and leading to unwanted erasure.

Innovation Solution

Incorporating an assist portion with a ferromagnetic main portion and a nonmagnetic assist portion recessed from the media-facing surface, which helps control throat height and divert magnetic flux, thereby mitigating flux shunting and wide area track erasure issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If side shields are fabricated with conventional processes, then manufacturing is simplified, but tails develop that increase effective throat height and cause flux shunting

Engineering Contradiction:

Improvefabrication simplicityVSAvoidthroat height control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent extracts the problematic tails from the side shields by introducing a nonmagnetic assist portion that terminates before the side shield tails. This separation removes the harmful extension while preserving the side shield structure, solving the throat height control issue without complicating fabrication

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The nonmagnetic assist portion acts as an intermediary element between the main pole and the side shields. It provides a controlled termination point for magnetic flux that prevents flux shunting through the side shield tails, while being fabricated in the same process sequence

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If side shield tails are present, then fabrication is easier, but magnetic flux shunting increases reducing recording accuracy

Engineering Contradiction:

Improvefabrication simplicityVSAvoidrecording accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The harmful magnetic flux shunting pathway through side shield tails is extracted and removed by introducing the nonmagnetic assist portion. This creates a break in the magnetic flux path before it reaches the problematic tail regions, eliminating the shunting effect while maintaining fabrication simplicity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention converts the potentially harmful side shield tails into a beneficial structure by using the same fabrication process to create both the side shields and the assist portion. The assist portion's controlled termination becomes the advantage, preventing flux shunting while the side shields retain their original fabrication benefits

Inventive Principle:

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

3Manufacturing precision

If side shield tails extend further, then fabrication tolerance is more forgiving, but effective throat height increases causing unwanted erasure

Engineering Contradiction:

Improvefabrication toleranceVSAvoideffective throat height

Core Design Contradiction:

Manufacturing precisionVSLength of stationary object

Solution Approach 1:

The nonmagnetic assist portion serves as an intermediary that defines a precise termination point for the magnetic flux path. This intermediary structure controls the effective throat height at a specific location before the side shield tails begin, preventing the tails from extending the magnetic flux path and causing erasure

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The write pole structure is segmented into distinct functional regions: the main pole, the nonmagnetic assist portion, and the side shields with tails. This segmentation allows each region to perform its specific function independently, with the assist portion controlling throat height while side shields provide flux shunting protection

Inventive Principle:

Principle #1Segmentation

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

The assist portion improves the performance of magnetic recording apparatuses by controlling throat height and reducing unwanted erasure, leading to enhanced recording accuracy and efficiency.

Implementation Method 1

the pole includes a ferromagnetic main portion and a nonmagnetic assist portion

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Implementation Method 2

These tails 17 also result in additional shunting of magnetic flux from the pole 20

Methodology Applied

Scientific EffectMagnetic flux: Magnetic Field

Data Source

PatentUS9558763B1Magnetic recording write apparatus having a pole including an assist portion extending in the cross-track direction

Publication Date: 2017.01.31 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

A magnetic write apparatus has a media-facing surface (MFS), a pole, side shield(s), a side gap and coil(s) for energizing the pole. The pole includes main and assist portions. The main portion is ferromagnetic, includes a pole tip and includes side surface(s) having a flare angle from the MFS. The pole tip occupies a portion of the MFS. The flare angle is nonzero and acute. The assist portion adjoins the main portion, extends from the main portion in a direction having a component in a cross-track direction, and has a depth of not more than three hundred nanometers. The side shield(s) occupy another portion of the MFS, have a back surface, and are between the assist portion and the MFS. The assist portion is conformal with the back surface of the side shield(s). The side gap is between the main portion of the pole and the side shield(s).