Read Head Lead-Under-Sensor Layout for Narrow-Track SNR
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Solution Overview
Problem
Existing read heads face challenges in achieving high signal-to-noise ratio (SNR) and recording density due to the narrowing of data tracks, leading to inferior performance in reading narrow tracks.
Innovation Solution
The read head design incorporates a bottom shield, multiple leads disposed over the bottom shield, a sensing layer, a free layer, side shields, and a top shield, with the leads positioned closely to the sensing layer to minimize parasitic electrical resistance and improve SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the width and pitch of data tracks are reduced to achieve higher recording density, then recording density is improved, but the signal-to-noise ratio deteriorates
Solution Approach 1:
The patent transitions from planar lead arrangement to a three-dimensional configuration where leads are positioned at different vertical levels relative to the sensing layer. The bottom lead extends beneath the sensing layer while side leads are positioned at elevated positions, creating vertical separation that reduces parasitic resistance without increasing lateral footprint, thus maintaining high recording density while improving SNR
Solution Approach 2:
The patent introduces a non-magnetic spacer layer as an intermediary between the sensing layer and the bottom lead. This spacer layer electrically isolates the bottom lead from the sensing layer, preventing parasitic current paths while maintaining close proximity for optimal magnetic coupling, thereby resolving the contradiction between low resistance and high recording density
2Quantity of substance
If narrower read elements are used to read narrow tracks, then recording density is improved, but the signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies different structural configurations to different parts of the read element. The bottom lead is positioned beneath the sensing layer with extended width for low resistance, while side leads are positioned at the edges with optimized geometry. This local differentiation allows each lead to be optimized for its specific function while maintaining overall compact dimensions for high recording density
Solution Approach 2:
The read element employs a composite structure combining multiple materials with different properties: magnetic layers for sensing, non-magnetic spacer layers for isolation, and conductive lead materials for low resistance. This composite approach enables simultaneous optimization of electrical conductivity, magnetic sensitivity, and geometric constraints for high-density operation
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 improved read head design enhances signal-to-noise ratio and recording density by reducing parasitic electrical resistance, enabling effective reading of narrow tracks.
Implementation Method 1
a sensing layer disposed in contact with at least the second lead
Data Source
AI summary
The present disclosure generally relates to a magnetic recording device comprising a read head. The read head comprises a bottom shield, a first lead, a second lead, and a third lead each disposed over the bottom shield at a media facing surface, a sensing layer disposed in contact with at least the second lead, an optional spacer layer, a free layer disposed over the sensing layer or optional spacer layer, a cap layer disposed on the free layer, side shields disposed adjacent to the free layer, and a top shield disposed over the free layer and side shields. In some embodiments, the bottom shield comprises the second lead, or is disposed in contact with the second lead. In other embodiments, the first, second, and third leads are spaced from the bottom shield by an insulating layer.