PMR Writer Trailing Shield High Saturation Layer
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Solution Overview
Problem
Current Perpendicular Magnetic Recording (PMR) writer designs face challenges in achieving improved write-field gradients, reducing adjacent track erasure (ATE), lowering on-track bit error rate (BER), and maintaining high flux writability before saturation, particularly due to flux leakage and premature pole tip saturation.
Innovation Solution
The design incorporates a trailing shield with a high saturation magnetic material layer on its leading edge, which reduces flux leakage and enhances return flux, using a non-conformal shape that differs from the main pole, and includes specific dimensions for the additional leading edge layer to optimize write gap and flux management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trailing shield is used in PMR writer design, then field gradients and ATE performance are improved, but flux leakage occurs between the shield and pole above the pole tip
Solution Approach 1:
The patent applies local quality by using a high saturation magnetic material layer specifically on the leading edge portion of the trailing shield where flux leakage occurs. This localized modification targets the specific problem area without changing the entire shield structure, allowing the rest of the shield to maintain its original flux-shielding function while the enhanced material layer specifically addresses flux leakage at the critical interface with the pole.
Solution Approach 2:
The patent employs composite materials by combining a high saturation magnetic material layer with the existing trailing shield structure. This composite approach creates a multi-layered shield system where the high saturation material layer (with saturation field >20 kG) works in conjunction with the base shield material, providing both the original shielding functionality and enhanced flux containment at the leading edge.
2Manufacturing precision
If the write gap is narrowed to improve write-field gradients, then writing precision is improved, but pole tip saturation occurs prematurely
Solution Approach 1:
The patent applies local quality by placing high saturation magnetic material specifically at the leading edge portion of the trailing shield where flux concentration and pole tip saturation occur. This localized enhancement creates a flux sink that prevents premature saturation at the pole tip, allowing the write gap to be narrowed for improved field gradients without sacrificing reliability.
Solution Approach 2:
The patent changes the magnetic saturation parameter by introducing material with a saturation field greater than 20 kG at the critical leading edge region. This parameter change increases the flux-carrying capacity of the shield at the most critical point, preventing premature saturation and enabling narrower write gaps for improved writing precision.
3Reliability
If fully wrapped around shields are used, then field gradients and ATE performance are improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by adding a high saturation magnetic material layer only to the leading edge portion of the trailing shield, rather than uniformly across the entire shield structure. This selective modification maintains the overall simplicity of the wrapped-around shield design while addressing the specific flux leakage issue at the critical interface with the pole.
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 improves write-field gradients, reduces ATE, lowers BER, and extends high flux writability by minimizing flux leakage and preventing premature saturation, thereby enhancing overall PMR writer performance.
Implementation Method 1
a layer of magnetic material with high magnetic saturation (high Bs) has been placed on the leading edge portion (50) of the trailing edge shield
Implementation Method 2
reduce flux leakage from pole to shield to provide a better return flux to the pole at the ABS
Data Source
AI summary
A method of forming a PMR (perpendicular magnetic recording) head that includes a tapered write pole that is fully surrounded by wrapped-around magnetic shields, including laterally disposed side shields, a trailing shield and a leading shield. A layer of high magnetic saturation material (high Bs) is formed on the leading edge of the trailing shield and extends rearward, away from the ABS plane to define a cross-sectional write gap shape that is not conformal with the shape of the tapered write pole. The cross-sectional shape of this shield layer enables it to absorb flux from the write pole so that the flux for writing is enhanced and concentrated at the area of the recording medium being written upon and does not extend to adjacent tracks or to downtrack positions at which such flux is not desired.