Perpendicular Magnetic Recording Head Pole Layer Shaping
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording face challenges in achieving accurate track width control and reducing the difference between physical and effective track widths, leading to issues like adjacent track erase and unwanted writing, due to difficulties in forming the desired shape of the pole layer and the expansion of magnetic flux.
Innovation Solution
A magnetic head design featuring a pole layer and a shield layer with a gap layer in between, where side shield layers made of magnetic material suppress magnetic flux extension, and a method of manufacturing involving a nonmagnetic metal layer and side shield layers to form a precise encasing section for the pole layer, allowing for accurate shaping and reduced effective track width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the track width is reduced to achieve higher recording density, then the linear recording density is improved, but the writing characteristics such as overwrite property suffer degradation
Solution Approach 1:
The pole layer is divided into two distinct portions: a track width defining portion with uniform width for precise track definition, and a wide portion with greater width for improved writing characteristics. This segmentation allows each portion to fulfill its specific function optimally, resolving the contradiction between narrow track width and good writing performance.
Solution Approach 2:
Different portions of the pole layer are given different widths to serve different purposes. The track width defining portion has a narrow uniform width for high recording density, while the wide portion has a greater width to maintain good overwrite property. This local variation in geometry allows simultaneous achievement of high density and good writing characteristics.
2Reliability
If the neck height is reduced to improve overwrite property, then the writing characteristics are improved, but the manufacturing precision of the pole layer shape becomes more difficult to control
Solution Approach 1:
The pole layer is segmented into a track width defining portion and a wide portion, with the neck height specifically defined for the track width defining portion. This segmentation allows precise control of the critical dimensions where needed while maintaining manufacturing feasibility.
3Object-generated harmful factors
If the pole layer is formed with a desired shape to reduce effective track width, then adjacent track erase is prevented, but the manufacturing complexity increases
Solution Approach 1:
The pole layer is divided into a track width defining portion and a wide portion, where the track width defining portion has a uniform width that is easier to manufacture with standard techniques. This segmentation simplifies the manufacturing of the critical track-defining region while still achieving the desired effective track width control to prevent adjacent track erase.
Solution Approach 2:
The uniform width portion of the pole layer is designed with constant dimensions that are optimized for manufacturing ease, while only the specific region affecting effective track width is given a particular geometry. This local optimization reduces overall manufacturing complexity while still preventing adjacent track interference.
4Measurement precision
If the end face of the track width defining portion is shaped asymmetrically to compensate for skew, then the writing accuracy is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The end face of the track width defining portion is designed with asymmetric dimensions: a first dimension in the track width direction and a second dimension in the writing direction, where the second dimension is larger. This asymmetry compensates for skew effects and improves writing accuracy while maintaining manufacturability through standard asymmetric machining techniques.
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 solution enables precise formation of the pole layer with a desired shape, effectively reducing the difference between physical and effective track widths, thereby improving writing characteristics and preventing adjacent track erase.
Implementation Method 1
side shield layers made of magnetic material suppress magnetic flux extension
Implementation Method 2
a nonmagnetic metal layer and side shield layers to form a precise encasing section for the pole layer
Data Source
AI summary
A magnetic head including an encasing layer having a groove; a nonmagnetic metal layer that has a sidewall located directly above the edge of the groove and that is disposed on a region of the encasing layer away from the medium facing surface; two side shield layers that have sidewalls located directly above the edge of the groove and that are disposed adjacent to the nonmagnetic metal layer on regions of the encasing layer closer to the medium facing surface than the nonmagnetic metal layer; and a pole layer. The pole layer is placed in an encasing section formed of the groove of the encasing layer, the sidewall of the nonmagnetic metal layer, and the sidewalls of the two side shield layers.