Magnetic Head Shield Alignment via Self-Aligned Gap Structure
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording systems face issues with adjacent track erase due to corner parts formed by the lower gap and side gaps, which concentrate magnetic flux and cause signal erasure, and unequal side shield effects resulting from misalignment of the mask during manufacturing.
Innovation Solution
A manufacturing method that forms a protrusion including the main magnetic pole and side gaps, using a developer-soluble resin layer and photolithography to create a mask that covers only the top surface of the protrusion, ensuring the lower gap ends align with the protrusion ends, preventing corner parts and maintaining side shield equality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a wrap-around shield is provided to suppress adjacent track erase, then recording density is improved, but corner parts are formed by the lower gap and side gaps that concentrate magnetic flux and cause signal erasure
Solution Approach 1:
The patent applies curvature by replacing the conventional rectangular corner parts with rounded corners having a radius of curvature R1. This curvature modification eliminates the sharp corners that concentrate magnetic flux, thereby preventing adjacent track erase while maintaining the wrap-around shield's ability to suppress such effects and improve recording density.
Solution Approach 2:
The patent applies local quality by making the gap width variable rather than uniform. The gap width is set to be smaller near the corner parts (where magnetic flux concentration occurs) and larger in the central region. This localized adjustment of gap width allows the structure to suppress adjacent track erase at critical locations while maintaining overall recording density performance.
2Productivity
If photolithography is used to form the shield structure, then manufacturing efficiency is improved, but mask misalignment occurs causing unequal side shield effects
Solution Approach 1:
The patent merges the formation of the lower gap and side gaps into a single integrated gap structure formed by one photolithography process. The gap is designed as a continuous nonmagnetic layer that connects the lower gap portion and side gap portions, eliminating the need for separate alignment steps and ensuring equal side shield effects while maintaining high manufacturing efficiency.
Solution Approach 2:
The patent employs self-aligned structures where the gap width and position are determined by the protrusion structure itself rather than requiring precise mask alignment. The gap is formed around the protrusion that defines the main magnetic pole position, allowing the structure to self-correct alignment variations and ensure equal side shield effects without additional alignment steps.
3Object-generated harmful factors
If the lower gap width is reduced to eliminate corner parts, then adjacent track erase is suppressed, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the gap width parameter spatially rather than uniformly. The gap width is set to a smaller value (first gap width) at corner regions to eliminate magnetic flux concentration, and a larger value (second gap width) in central regions. This parameter variation is achieved through a single photolithography process using an appropriately designed mask pattern, avoiding increased manufacturing complexity.
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 method suppresses adjacent track erase by eliminating corner parts and ensures equal side shield effects, improving recording density and overwrite properties by maintaining the shape and alignment of critical magnetic head components.
Implementation Method 1
a coil that produces a magnetic field corresponding to data to be recorded on the recording medium; a main magnetic pole that allows a magnetic flux corresponding to the magnetic field produced by the coil to pass, and produces a recording magnetic field
Implementation Method 2
a shield having an end face that is located in the medium facing surface to wrap around the end face of the main magnetic pole... The wrap-around shield takes in a magnetic flux that is generated from the end face of the main magnetic pole located in the medium facing surface and that expands in directions other than the direction perpendicular to the plane of the recording medium
Implementation Method 3
a gap made of a nonmagnetic material and provided between the main magnetic pole and the shield... The gap includes a lower gap, an upper gap, and first and second side gaps
Data Source
AI summary
A manufacturing method for a magnetic head includes the steps of: forming a structure on a lower shield, the structure including a lower gap, a main magnetic pole and first and second side gaps; forming first and second side shields; forming an upper gap; and forming an upper shield. In the step of forming the structure, an initial lower gap layer is formed on the lower shield, the initial lower gap layer including a pre-lower-gap portion, and two to-be-removed portions that are located on opposite sides of the pre-lower-gap portion. Then, a protrusion including the main magnetic pole and the first and second side gaps is formed on the pre-lower-gap portion. With the top surface of the protrusion covered with a mask, the initial lower gap layer is etched in part to thereby form the lower gap.