Magnetic Head Air Bearing Surface Contamination Control
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Solution Overview
Problem
In hard disk drives (HDDs), the small gap between the magnetic head and disk surface increases the risk of contamination trapping and scratches due to the smaller fly height required for higher recording density, especially with contamination particles of 60 to 100 nm, which can lead to device failure.
Innovation Solution
The magnetic head's air bearing surface is designed with a concave and convex structure, including a negative pressure generating groove, leading and trailing pads, and a reduced uppermost surface area in specific regions to minimize contamination trapping and generate stable flying forces, reducing the risk of scratches and device failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the amount of fly (gap) is reduced to increase recording density, then recording density is improved, but the risk of contamination trapping and scratches increases
Solution Approach 1:
The air bearing surface is designed with different regions having different functions: a first region with a larger area that generates positive pressure to maintain stable flying, and a second region with a smaller area that reduces contamination trapping risk. This local differentiation allows the slider to maintain both small overall fly height for high recording density and reduced contamination risk in critical areas.
Solution Approach 2:
The air bearing surface is segmented into multiple functional regions: a first region (larger area) and a second region (smaller area), each serving different purposes. The first region primarily generates flying force while the second region is optimized to minimize contamination trapping, allowing the system to achieve both high recording density and improved reliability.
2Force
If the gap between the uppermost surface and magnetic disk surface is reduced to increase flying force, then flying force is improved, but contamination trapping risk increases
Solution Approach 1:
The air bearing surface uses local quality differentiation where the first region has a larger area to generate sufficient positive pressure and flying force, while the second region has a smaller area specifically designed to reduce contamination trapping. This allows the system to maintain strong flying force while minimizing contamination risk in the critical second region.
Solution Approach 2:
The design converts the potential harm of small gap (contamination trapping) into a benefit by strategically placing the smaller second region in a location where contamination trapping is most problematic, while the larger first region continues to provide the necessary flying force. The harmful effect of small gap is thus localized and managed.
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 effectively reduces the occurrence of scratches and improves the reliability of the magnetic head and HDD by minimizing contamination trapping and maintaining stable flying forces, with a significant reduction in non-functional head occurrence probability.
Implementation Method 1
a force (positive pressure) to cause the slider to fly from the magnetic disk surface acts on the ABS of the slider by the airflow generated between the rotating magnetic disk and the slider
Implementation Method 2
a negative pressure generating groove formed at a central portion in the first direction and extending in a second direction orthogonal to the first direction
Data Source
AI summary
According to one embodiment, a magnetic head includes a slider including an air bearing surface which includes a plurality of uppermost surfaces each constituting a pressure generating surface and a plurality of other surfaces different in height from the uppermost surfaces, an inflow end, and an outflow end, and a head portion provided at the outflow end. The air bearing surface includes a negative pressure generating groove, a leading pad having the uppermost surface, and a trailing pad having the uppermost surface. The uppermost surface in a region between a tip portion of the trailing pad and the outflow end includes only the trailing pad.