Magnetic Adhesion Layer for Disk Head Write Field Decay

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Solution Overview

Problem

In disc drive systems, the magnetic field decay with increasing head-to-media spacing negatively affects writeability and readability, leading to reduced bit writing performance and increased Bit Error Rate (BER).

Innovation Solution

Incorporating a magnetic adhesion layer at the air bearing surface of the device, with a magnetic overcoat that enhances the relative magnetic permeability, thereby preserving magnetic field strength and improving writeability and readability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the flying height is minimized to maximize areal recording density, then the head-to-media spacing is reduced, but the magnetic field decay increases leading to reduced writeability and readability

Engineering Contradiction:

Improveareal recording densityVSAvoidwriteability and readability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies composite materials by creating a multi-layer structure consisting of a non-magnetic overcoat layer (such as DLC) combined with a magnetic adhesion layer. This composite structure allows the overcoat to provide protective functions while the magnetic adhesion layer maintains magnetic field strength, thus resolving the contradiction between minimizing flying height for higher density and maintaining reliability for writeability and readability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The magnetic adhesion layer acts as an intermediary between the non-magnetic overcoat and the head magnetic surface. This intermediary layer preserves magnetic field strength across the head-to-media interface, allowing the overcoat to be present without degrading magnetic performance, thus enabling both high areal recording density and maintained writeability/readability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If a DLC overcoat is applied to protect underlying metals and alloys, then wear and corrosion protection is improved, but the head-to-media separation distance increases reducing data reading and writing efficiency

Engineering Contradiction:

Improvewear and corrosion protectionVSAvoiddata reading and writing efficiency

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent uses composite materials by combining a thin DLC overcoat layer with a magnetic adhesion layer. The DLC layer provides wear and corrosion protection while the magnetic adhesion layer compensates for the increased separation distance by maintaining magnetic field strength, thus achieving both protection and maintained data efficiency.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by making the magnetic adhesion layer specifically at the air bearing surface where magnetic field interaction occurs. This localized magnetic layer ensures that protection functions are provided by the overcoat while magnetic performance is maintained at the critical interface with the media.

Inventive Principle:

Principle #3Local quality

3Strength

If the DLC overcoat thickness is increased to enhance protection, then wear and corrosion resistance is improved, but the head-to-media separation distance increases further reducing transducer efficiency

Engineering Contradiction:

Improvewear and corrosion resistanceVSAvoidtransducer efficiency

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies composite materials by creating a structured multi-layer system where a DLC overcoat is combined with a magnetic adhesion layer. This allows optimization of overcoat thickness for protection while the magnetic adhesion layer ensures magnetic field strength is maintained, preventing degradation of transducer efficiency.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The magnetic adhesion layer serves as an intermediary that compensates for the increased head-to-media separation caused by thicker DLC overcoats. By maintaining magnetic field strength across this increased distance, the intermediary layer allows enhanced protection without sacrificing transducer efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 reduces write field decay rate, enhancing bit writing performance and reducing Bit Error Rate (BER) by maintaining magnetic field strength across the head-to-media interface.

Implementation Method 1

the magnetic adhesion layer is between the at least a portion of the surface of the writer portion and the overcoat

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

with a magnetic overcoat that enhances the relative magnetic permeability, thereby preserving magnetic field strength

Methodology Applied

Scientific EffectMagnetic permeability:

Data Source

PatentUS9570101B2Magnetic adhesion layer and method of forming same

Publication Date: 2017.02.14 SEAGATE TECH LLC

AI summary

A device having an air bearing surface and a method of forming the device are disclosed. The device can include a writer portion including a surface at the air bearing surface of the device, a magnetic adhesion layer disposed proximate at least a portion of the surface of the writer portion, and an overcoat disposed proximate at least a portion of the magnetic adhesion layer such that the magnetic adhesion layer is between the at least a portion of the surface of the writer portion and the overcoat.