Magnetic Head Pole Layer Segmentation for Skew Control
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording systems face issues with skew, leading to adjacent track erase and unwanted writing, which degrade recording density and signal quality due to inadequate control over write characteristics.
Innovation Solution
A magnetic head design featuring a pole layer with a first portion and a second portion of varying thickness, where the second portion is thicker and farther from the medium facing surface, and a shield structure with nonmagnetic and gap layers to manage magnetic flux and prevent flux leakage, allowing for precise control of write characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the end face of the pole layer is formed into a shape where the backward side is shorter than the forward side to prevent skew, then adjacent track erase is suppressed, but the cross-sectional area of the pole layer is reduced and write characteristics deteriorate
Solution Approach 1:
The pole layer is divided into a first pole layer and a second pole layer with different thicknesses. The first pole layer has a smaller thickness at the backward side to prevent skew and adjacent track erase, while the second pole layer has a larger thickness at the forward side to maintain write characteristics and magnetic flux generation capability.
Solution Approach 2:
Different portions of the pole layer are given different local properties through varying thickness. The backward portion has smaller thickness for skew prevention, while the forward portion has larger thickness for maintaining magnetic flux and write performance, creating local optimization throughout the structure.
2Reliability
If the entire pole layer is made thin to prevent skew, then adjacent track erase is reduced, but the magnetic flux introduction capability is reduced and write characteristics degrade
Solution Approach 1:
The pole layer is segmented into two distinct portions with different thickness characteristics. The first portion (backward side) is thin to prevent skew, while the second portion (forward side) is thick to maintain magnetic flux introduction capability and write power.
Solution Approach 2:
The pole layer exhibits local quality variations where thickness is optimized for different functional requirements: thinness at the backward side for skew prevention and thickness at the forward side for magnetic flux generation and write capability.
3Manufacturing precision
If the cross-sectional area of the pole layer is reduced to control skew, then write precision is improved, but the overwrite property and write characteristics are degraded
Solution Approach 1:
The pole layer is divided into segments with different cross-sectional areas. The first pole layer segment has smaller cross-sectional area for precision control, while the second pole layer segment has larger cross-sectional area for maintaining overwrite property and write reliability.
Solution Approach 2:
Different segments of the pole layer have locally optimized cross-sectional areas matched to their functional needs: precision-oriented thinness at the backward side and power-oriented thickness at the forward side for overwrite operations.
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 enhances write characteristics by preventing skew-related issues, improving recording density and signal quality by accurately controlling the positional relationship between shield and pole layer components.
Implementation Method 1
a coil for generating a magnetic field corresponding to data to be written on a recording medium
Implementation Method 2
a pole layer for allowing a magnetic flux corresponding to the magnetic field generated by the coil to pass therethrough and generating a write magnetic field for writing the data on the recording medium
Implementation Method 3
The first and the second shield have a function of preventing a magnetic flux from reaching the recording medium, the magnetic flux having been generated from the end face of the pole layer
Data Source
AI summary
A magnetic head includes a pole layer, a first and a second shield disposed to sandwich the pole layer, and a nonmagnetic layer disposed around the first shield. The pole layer includes a first portion having an end face located in a medium facing surface, and a second portion that is located farther from the medium facing surface than is the first portion. The second portion is greater in thickness than the first portion. A bottom surface of the second portion is located closer to a substrate than is a bottom surface of the first portion. The first shield has a first top surface portion opposed to the bottom surface of the first portion with the first gap layer in between. The nonmagnetic layer has a second top surface portion opposed to the bottom surface of the second portion with the first gap layer in between. A difference in level is formed between the first and the second top surface portion such that the second top surface portion is located closer to the substrate than is the first top surface portion.