Magnetic Head Side Shield Segmentation for Perpendicular Recording
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording face challenges in maintaining high recording densities due to unwanted erasure phenomena, where signals on adjacent tracks are erased or attenuated during writing, and controlling the shape of side shields to increase the cross-sectional area of the main pole near the medium facing surface becomes difficult with miniaturization.
Innovation Solution
The magnetic head design includes a write shield with a pair of first and second side shields, where the second side shields are in contact with the first side shields and have a continuous third side wall, allowing the distance between these walls to increase with distance from the medium facing surface, and the main pole has a varying shape to increase its cross-sectional area near the medium facing surface, using different saturation magnetic flux densities for the side shields materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the end face of the main pole is made smaller in width to increase recording density, then recording density is improved, but the cross-sectional area of the main pole near the medium facing surface decreases, worsening write characteristics
Solution Approach 1:
The side shields are divided into two pairs: first side shields closer to the medium facing surface and second side shields farther away. This segmentation allows independent optimization of each pair's shape and position, enabling the main pole to have a smaller end face width for high recording density while maintaining a larger cross-sectional area near the medium facing surface through the first side shields' configuration
Solution Approach 2:
The side shields are positioned at different distances from the medium facing surface in the depth dimension, creating a three-dimensional shield structure. This dimensional approach allows the side shields to control the magnetic field distribution without directly constraining the main pole's end face width, resolving the conflict between small end face width and large cross-sectional area
2Reliability
If the shapes of the side shields are accurately controlled to increase the cross-sectional area of the main pole, then write characteristics are improved, but the device complexity increases, especially with miniaturization
Solution Approach 1:
Dividing the side shields into two pairs simplifies the shape control problem by allowing each pair to have simpler, more standardized geometries. The first side shields can be optimized for one function while the second side shields handle another, reducing the overall complexity compared to controlling a single complex shield shape
Solution Approach 2:
Different regions of the side shield structure are given different properties: the first side shields are positioned and shaped to maximize cross-sectional area near the medium facing surface, while the second side shields are configured to maintain field control at greater distances. This local optimization allows each component to be simpler while achieving the overall complex function
3Ease of manufacture
If standard side shield structures are used to simplify manufacturing, then ease of manufacture is improved, but unwanted erasure increases, reducing recording density
Solution Approach 1:
The segmented side shield structure allows each pair to be manufactured using similar processes, maintaining ease of manufacture through repetition of proven techniques. The first and second side shields can both be fabricated using the same deposition and patterning methods, avoiding the need for entirely new manufacturing processes
Solution Approach 2:
The side shields act as intermediary structures that mediate between the write head and the recording medium. By introducing these intermediate magnetic field control elements, unwanted erasure is reduced without requiring direct modification of the main pole structure, preserving standard manufacturing approaches for the core write head components
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 configuration effectively increases the cross-sectional area of the main pole near the medium facing surface, reducing unwanted erasure and improving write characteristics by maintaining higher recording densities and better write performance.
Implementation Method 1
a coil configured to generate a magnetic field corresponding to data to be written on the recording medium
Implementation Method 2
a main pole configured to pass a magnetic flux corresponding to the magnetic field generated by the coil and generate a write magnetic field for writing the data on the recording medium
Implementation Method 3
a write shield formed of a magnetic material... The pair of first side shields and the pair of second side shields are in contact with each other
Data Source
AI summary
A write shield of a magnetic head includes a pair of first side shields and a pair of second side shields. The pair of first side shields each include a first side wall and a second side wall. The pair of second side shields each include a third side wall. The third side wall of one of the pair of second side shields is continuous with the first side wall of one of the pair of first side shields. The third side wall of the other of the pair of second side shields is continuous with the first side wall of the other of the pair of first side shields.