Thermal Shunt for E-Antenna NFT Heat Dissipation
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Solution Overview
Problem
Heat-assisted magnetic recording heads face degradation due to heat-induced issues in near field transducers (NFTs) and write pole lips, leading to potential head failure, as excess heat is not effectively dissipated, limiting the ability to write data to small bit sizes with high coercivity magnetic media.
Innovation Solution
A thermal shunt is introduced between the E-antenna near field transducer (NFT) and the return pole, utilizing a multi-piece structure with a trapezoidal gap filled with a dielectric like alumina to diffuse excess heat away from the NFT, providing additional surface area for convection and reducing peak temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If optical energy is concentrated to a nanometer-sized spot using a near field transducer to heat the media, then the ability to write data to high coercivity magnetic media is improved, but heat-induced degradation of the NFT and write pole lip occurs leading to head failure
Solution Approach 1:
The patent extracts the harmful heat away from the NFT by introducing a thermal shunt that conducts excess heat from the NFT to a heat sink, separating the heat generation function from the optical concentration function to prevent thermal degradation
Solution Approach 2:
The thermal shunt acts as an intermediary component between the NFT and the heat sink, facilitating heat transfer from the NFT without interfering with the optical field concentration, thereby protecting the NFT from thermal damage while maintaining writing capability
2Power
If the magnetic field is made strong enough to write data to small bit sizes with high coercivity media, then the writing capability is improved, but the superparamagnetic effect limits further reduction of bit size
Solution Approach 1:
The patent changes the temperature parameter of the magnetic media by heating it above the Curie temperature using optical energy, which temporarily reduces the coercivity and allows writing to smaller bit sizes without being limited by the superparamagnetic effect
Solution Approach 2:
The patent applies periodic heating cycles where the media is heated above the Curie temperature only during the writing operation, then cooled back down, allowing repeated writing operations to high coercivity media with small bit sizes
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 thermal shunt effectively reduces the peak temperature rise of the NFT by up to 24%, mitigating degradation and enhancing the ability to write data to high coercivity media without adverse effects on optical performance or magnetic field generation.
Implementation Method 1
A thermal shunt is positioned between an E-antenna near field transducer (NFT) and a return pole, to draw excess heat away from the NFT
Implementation Method 2
provide surface area for convection of heat away from the head slider surface
Data Source
AI summary
In a heat-assisted magnetic recording head for use in a hard disk drive, a thermal shunt is positioned between an E-antenna near field transducer (NFT) and a return pole, to draw excess heat away from the NFT region. The thermal shunt comprises two portions separated by a gap that has a trapezoidal cross-section, where the NFT-side of the gap is wider than the return pole-side of the gap.