HAMR Write Pole Galvanic Corrosion Isolation

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Solution Overview

Problem

Galvanic corrosion in heat assisted magnetic recording (HAMR) heads occurs due to electrical contact between high magnetic moment write poles and noble metal near field transducers/heatsinks, leading to electrochemical corrosion and head failure.

Innovation Solution

Incorporation of an electrical isolation layer between the write pole and the near field transducer-heat sink (NFT-HS), along with a power source to electrically bias the write pole, minimizes or eliminates galvanic corrosion by preventing electrical contact and using a diffuser for effective heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the write pole and NFT-HS are electrically contacted to enable heat dissipation, then thermal performance is improved, but galvanic corrosion occurs leading to head failure

Engineering Contradiction:

Improveheat dissipationVSAvoidhead failure due to galvanic corrosion

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

An electrical isolation layer is introduced between the write pole and NFT-HS to prevent direct electrical contact and galvanic corrosion, while still allowing thermal energy to transfer from the NFT-HS to the write pole for heat dissipation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrical bias is adjusted to create a potential difference between the write pole and second structure, changing the electrical parameters to prevent galvanic corrosion by making the write pole the cathode in the electrochemical cell

Inventive Principle:

Principle #35Parameter changes

2Reliability

If an electrical isolation layer is added to prevent galvanic corrosion, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvereduction of galvanic corrosionVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A thin film electrical isolation layer is used to prevent galvanic corrosion without significantly increasing device complexity. The thin film nature allows it to be integrated into the existing HAMR head structure with minimal additional complexity

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If electrical bias is applied to prevent galvanic corrosion, then reliability is improved, but energy consumption increases

Engineering Contradiction:

Improveprevention of electrochemical corrosionVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The electrical bias is applied selectively and partially - only enough potential difference is created to prevent galvanic corrosion by making the write pole the cathode, rather than applying excessive voltage. This minimizes energy consumption while achieving the corrosion protection goal

Inventive Principle:

Principle #16Partial or excessive action

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 solution significantly reduces galvanic corrosion, maintaining the thermal performance of the NFT-HS while preventing electrochemical reactions, thereby enhancing the reliability and longevity of HAMR heads.

Implementation Method 1

Methodology Applied

Scientific EffectGalvanic corrosion: Electrochemiluminescence

Implementation Method 2

a near field transducer-heat sink (NFT-HS), the NFT-HS including a noble metal

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS8817407B2Heat assisted magnetic recording head

Publication Date: 2014.08.26 SEAGATE TECH LLC

AI summary

An apparatus that includes a write pole, the write pole including a magnetic material; a near field transducer-heat sink (NFT-HS), the NFT-HS including a noble metal; and a power source configured to electrically bias the write pole with respect to a second structure.