Head Slider Air Bearing Surface Recess Design for Fly Height Stability
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Solution Overview
Problem
Existing head sliders in hard disk drives face issues with lubricant pick-up, high peak pressure leading to fly height variations, and insufficient stiffness, which result in poor magnetic interfacing and potential catastrophic failures due to distortion.
Innovation Solution
A head slider design featuring a deep recess in front of the trailing pad with an island pad, reducing peak pressure and mitigating mid-disk hump without compromising other performance parameters, achieved through a specific air bearing surface configuration and etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the head slider uses a conventional air bearing surface design, then the structure is simple and easy to manufacture, but it results in high peak pressure causing fly height variations and lubricant pick-up
Solution Approach 1:
The air bearing surface is segmented into multiple functional zones including a trailing pad, leading pad, side pads, and intermediate regions with varying etch depths. This segmentation allows different regions to perform specific functions: the trailing pad with deeper etch reduces peak pressure, while other pads maintain necessary lift and stability, thereby improving fly height stability without excessive complexity
Solution Approach 2:
Different regions of the air bearing surface are given different local properties through selective etching. The trailing pad has a deeper etch depth to reduce peak pressure and lubricant pick-up, while leading and side pads have different etch depths to maintain overall bearing performance. This local differentiation resolves the contradiction by optimizing specific areas rather than uniformly increasing complexity
2Reliability
If the head slider increases stiffness to prevent distortion, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent modifies physical parameters of the air bearing surface, specifically the etch depth and pattern, to optimize performance. By changing the etch depth parameter in specific regions, the design achieves better pressure distribution and fly height stability, improving reliability without requiring additional structural elements that would increase complexity
3Measurement precision
If the head slider operates with higher peak pressure to maintain fly height, then positioning accuracy improves, but lubricant pick-up increases causing failures
Solution Approach 1:
The trailing pad is designed with a deeper etch depth compared to other regions, creating a local quality difference. This deeper etch in the trailing pad specifically addresses lubricant pick-up by modifying the pressure distribution in the critical trailing region, while other pads maintain their original characteristics to preserve positioning accuracy
Solution Approach 2:
The patent converts the potentially harmful effect of peak pressure into a beneficial pressure distribution pattern. By strategically placing deeper etches in the trailing pad, the design uses the pressure gradient to reduce lubricant pick-up while maintaining necessary fly height, effectively converting what could be a harmful high-pressure zone into a beneficial pressure management solution
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 design reduces lubricant pick-up, minimizes mid-disk hump, and maintains fly height stability across the disk, preventing distortion and improving magnetic interfacing efficiency.
Implementation Method 1
The head slider includes an air bearing surface (ABS) designed to generate an air bearing force that counteracts a preload bias urging the head slider toward the disk. The head slider flies above and out of contact with the disk as a result of the ABS.
Data Source
AI summary
A head slider for supporting a head over a magnetic disk in a hard disk drive, and a method of making the head slider are disclosed. The air bearing surface (ABS) of the head slider includes a relatively deep recess in front of a trailing pad and an island pad. A recess is formed between the trailing pad and the island pad of the ABS. In operation, the recess may reduce the peak pressure of the ABS, resulting in a reduced mid disk (MD) hump without a reduction in other performance parameters. The reduction in peak pressure may also reduce lubrication pick-up from the magnetic disk.