Thin-Film Magnetic Head Shield Layer Curvature for Flux Concentration
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Solution Overview
Problem
Existing thin-film magnetic heads for perpendicular and longitudinal magnetic recording face challenges in suppressing unwanted writing or erasing due to magnetic flux concentration, particularly at the edges of shield and magnetic pole layers, which affects recording density and data integrity.
Innovation Solution
The design incorporates magnetic layers with obliquely spreading edges and rounded or obtuse corner shapes at the head end surface to reduce magnetic flux concentration, preventing unwanted writing or erasing by eliminating sharp angles and promoting a surface without right or sharp angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If shield/magnetic pole layers are used in thin-film magnetic heads for perpendicular magnetic recording, then magnetic flux can be generated for writing data, but magnetic flux concentration occurs at the edges and corners of these layers causing unwanted writing or erasing in positions distant from the track to be written
Solution Approach 1:
The patent applies curvature by rounding the corner portions of the shield layer and magnetic pole layer instead of using sharp right angles. Specifically, the corner portions are formed with a curved surface having a radius of curvature R where 0.5 μm ≤ R ≤ 2.0 μm. This curvature eliminates the flux concentration that occurs at sharp corners, thereby preventing unwanted writing or erasing in positions distant from the intended track while maintaining high recording density.
Solution Approach 2:
The patent applies local quality by making the corner portions of the shield and magnetic pole layers have different shapes from the main body. The corner portions are specifically rounded with controlled radius of curvature, while the rest of the layers maintain their functional geometry. This localized modification targets the specific problem area (corner flux concentration) without altering the overall head structure or sacrificing recording performance.
2Ease of operation
If the head flies on the magnetic recording medium with a predetermined spacing, then read and write operations can be performed, but external magnetic field or write magnetic field causes unwanted writing or erasing in positions distant from the track to be written
Solution Approach 1:
By rounding the corner portions of the shield and magnetic pole layers with a controlled radius of curvature (0.5 μm ≤ R ≤ 2.0 μm), the patent eliminates the flux concentration that would otherwise occur at sharp corners. This curvature modification prevents external magnetic fields and write fields from concentrating at the corners and causing unwanted writing or erasing in positions distant from the intended track, thereby improving resistance to external magnetic field influence while maintaining operational ease.
3Ease of manufacture
If conventional shield layers and magnetic pole layers with right angles are used, then manufacturing is simplified, but magnetic flux concentrates at the corners and ends of edges on the air bearing surface side
Solution Approach 1:
The patent introduces curvature to the corner portions of the shield and magnetic pole layers with a specifically controlled radius of curvature (0.5 μm ≤ R ≤ 2.0 μm). This geometric modification prevents magnetic flux concentration at corners and ends of edges on the air bearing surface side. The curved corners can be formed using standard thin-film deposition and patterning techniques, maintaining ease of manufacture while achieving precise flux distribution control.
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
This design effectively suppresses magnetic flux concentration, enhancing recording density and data integrity by preventing unwanted writing or erasing, even under high recording density conditions.
Implementation Method 1
a rather large loop of magnetic flux may be generated through the soft-magnetic backing layer and the auxiliary magnetic pole layer. The magnetic flux of the generated loop has a tendency to concentrate near both ends of the edge on the air bearing surface (ABS) side of the auxiliary magnetic pole layer
Data Source
AI summary
Provided is a thin-film magnetic head in which the concentration of magnetic flux in the shield layer and the magnetic pole layer is suppressed. The thin-film magnetic head comprises a plurality of magnetic layers that have front surfaces reaching a head end surface on the ABS side. Further in this head, at least one of the plurality of magnetic layers has a shape in which: each of edges corresponding to both side surfaces extends so as to spread obliquely rearward with each other from an end of a straight edge in a track width direction corresponding to the front surface; and the front surface reaching the head end surface has a shape in which upper and lower corner portions in each of both end portions in the track width direction form obtuse angles or rounded shapes.