Thin-Film Magnetic Head Shield Layer Segmentation
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Solution Overview
Problem
Existing thin-film magnetic heads in perpendicular recording mode face challenges with external magnetic field resistance, leading to inadvertent erasure of data and pole tip protrusion due to heat and temperature changes, which affect recording density and stability.
Innovation Solution
A thin-film magnetic head design with a write shield layer having thicker ends on the air bearing surface to enhance external magnetic field resistance, combined with a multilayer structure for the magnetic pole and shield layers to prevent magnetic flux spread and thermal issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin-film magnetic head uses a conventional single-pole type structure or standard shield layer configuration, then the device complexity is low and manufacturing is easier, but external magnetic field resistance is poor leading to inadvertent data erasure and pole tip protrusion
Solution Approach 1:
The shield layer is divided into multiple segments with different thicknesses along the track width direction. Specifically, the shield layer has a first thickness in a first region and a second thickness in a second region, creating a non-uniform structure that provides enhanced external magnetic field resistance where needed while maintaining manufacturing feasibility through defined regional variations rather than completely complex geometries
Solution Approach 2:
Different regions of the shield layer are given different local properties through varying thickness. The first region has a first thickness optimized for certain magnetic field conditions while the second region has a second thickness optimized for other conditions, allowing each region to perform its specific function optimally without requiring complete structural redesign
2Reliability
If the shield layer thickness is increased uniformly to improve external magnetic field resistance, then inadvertent data erasure is reduced, but pole tip protrusion due to thermal expansion increases
Solution Approach 1:
The shield layer thickness is varied locally across different regions rather than being uniformly increased. This allows certain regions to have greater thickness for enhanced magnetic field resistance and data protection, while other regions maintain smaller thickness to minimize thermal expansion and pole tip protrusion, thus resolving the contradiction between data protection and thermal stability
3Reliability
If a non-uniform shield layer thickness configuration is implemented to optimize magnetic field resistance, then external magnetic field resistance improves, but manufacturing precision requirements increase
Solution Approach 1:
The shield layer is segmented into distinct regions with defined thickness variations. This segmentation approach allows for controlled non-uniformity that can be implemented through standard thin-film deposition techniques by defining specific deposition parameters for different regions, thereby achieving the desired thickness profile without requiring excessively complex manufacturing processes or precision beyond current capabilities
Solution Approach 2:
The thickness parameter of the shield layer is changed across different regions to optimize performance. By systematically varying this single parameter (thickness) in a controlled manner across defined regions, the patent achieves improved external magnetic field resistance while maintaining manufacturability, as thickness control is a well-established parameter in thin-film fabrication processes
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 inadvertent data erasure and pole tip protrusion, improving external magnetic field resistance and maintaining recording density while stabilizing magnetic operation performance.
Implementation Method 1
a write shield layer, which is located on a side of the magnetic pole layer in the medium traveling direction, and extends from the surface opposite to the recording medium toward the rear
Implementation Method 2
a thin-film magnetic recording head comprising a magneto-resistive effect device adapted to read the magnetic field intensity of a magnetic recording medium
Implementation Method 3
a thin-film coil adapted to generate a recording magnetic flux
Data Source
AI summary
A write shield layer that forms a part of a thin-film magnetic head is set with respect to the widthwise full length W thereof lying substantially on an air bearing surface that is opposite to the recording medium such that when the full length W is trisected, the maximum thickness H1/3side thereof in a range of widthwise ⅓W size positioned at both ends thereof is larger than the average thickness Hm of the whole write shield layer from the air bearing surface up to the rear (H1/3side>Hm), so that the so-called external magnetic field resistance is improved, and inadvertent erasure of the information already recorded in the recording medium is avoided as much as possible. Besides, the PTP (pole tip protrusion) phenomenon arising from the generation of heat from coils, and external temperature changes can be held back.