Perpendicular Magnetic Head Pole Layer with Inclined Top Surface
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording face challenges in preventing skew-related issues, such as adjacent track erasing and unwanted writing, due to difficulties in precisely defining the track width and maintaining effective write characteristics as the neck height decreases.
Innovation Solution
A magnetic head design featuring a pole layer with a top surface comprising a first portion closer to the substrate and a second portion farther away, where the angle of inclination increases with distance from the medium facing surface, and a nonmagnetic layer with a specific angle of inclination, along with a gap layer and shield, to enhance magnetic flux introduction and reduce flux leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the neck height is reduced to improve overwrite property, then the overwrite property is improved, but the track width definition precision deteriorates
Solution Approach 1:
The pole layer is designed with non-uniform thickness, where the first portion (closer to substrate) has a different thickness than the second portion (closer to medium facing surface). This local variation in thickness allows the track width defining portion to maintain precise track width definition at the medium facing surface while having sufficient magnetic flux conducting area in the thicker first portion, thus resolving the contradiction between neck height reduction for overwrite property and track width definition precision.
2Productivity
If the track width is reduced to achieve higher recording density, then the recording density is improved, but the write characteristics deteriorate
Solution Approach 1:
The pole layer employs local quality variation with a thicker first portion that extends deeper into the substrate. This thicker region provides enhanced magnetic flux conducting capability, which compensates for the reduced track width and maintains excellent write characteristics such as overwrite property, while still achieving high recording density through the narrowed track width at the medium facing surface.
Solution Approach 2:
The invention addresses the track width limitation by introducing a vertical dimension variation in the pole layer thickness. Instead of uniformly reducing track width across all depths, the design maintains a thicker profile in the vertical direction (first portion closer to substrate) to preserve magnetic flux capacity, while achieving narrow track width at the critical medium facing surface level.
3Reliability
If the neck height is reduced to improve overwrite property, then the overwrite property is improved, but the magnetic flux introduction capability deteriorates
Solution Approach 1:
The pole layer is designed with local quality variation where the first portion (closer to substrate) has greater thickness to provide enhanced magnetic flux conducting area, while the second portion (closer to medium facing surface) has reduced thickness to define precise track width. This local thickness variation enables the structure to maintain both improved overwrite property through narrow effective track width and sufficient magnetic flux introduction capability through the thicker first portion.
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 prevents skew-related problems, improves write characteristics by allowing greater magnetic flux to the medium facing surface, and maintains precise track width definition with moderate variations in write characteristics despite polishing variations.
Implementation Method 1
a coil for generating a magnetic field corresponding to data to be written on the recording medium
Implementation Method 2
the pole layer 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
a shield made of a magnetic material and having an end face located in the medium facing surface at a position forward of the end face of the pole layer along a direction of travel of the recording medium
Data Source
AI summary
A top surface of a pole layer of a magnetic head includes: a first portion having a first edge located in a medium facing surface and a second edge opposite thereto; and a second portion located farther from the medium facing surface than the first portion and connected to the first portion at the second edge. The distance from a substrate to an arbitrary point on the first portion increases with increasing distance from the medium facing surface to the arbitrary point. The angle of inclination of the first portion taken at the arbitrary point with respect to a direction perpendicular to the medium facing surface increases stepwise or continuously with increasing distance from the medium facing surface to the arbitrary point. The angle of inclination taken at the first edge is greater than zero degree. The second portion extends in a direction substantially perpendicular to the medium facing surface.