Thin-Film Magnetic Head Shield Depth Variation for ATE Reduction
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Solution Overview
Problem
Conventional thin-film magnetic heads with a Double Write Shield (DWS) structure face challenges in reducing Adjacent Track Erasure (ATE) and Wide Area Track Erasure (WATE) while maintaining read/write separation (RWS) within a certain dimension range and simplifying manufacturing processes to increase production efficiency.
Innovation Solution
A thin-film magnetic head design featuring a main magnetic pole layer, a write shield layer, and a thin-film coil with a substrate side coil layer, where the leading shield part has a tilted rear end face and a depth smaller than the substrate side shield part, and a middle insulating layer wraps around the medium-opposing surface, reducing magnetic flux leakage and simplifying manufacturing steps by eliminating unnecessary shield layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shield layers are formed on both trailing side and leading side of the main magnetic pole layer (DWS structure), then ATE and WATE are reduced, but the read/write separation (RWS) dimension becomes difficult to control within required range
Solution Approach 1:
The shield magnetic layer is segmented into three distinct parts: leading shield part, substrate side shield part, and linking shield part. Each part serves a specific function - the leading shield part reduces ATE/WATE, the substrate side shield part maintains RWS dimension, and the linking shield part connects them. This segmentation allows independent optimization of each component to resolve the contradiction between reducing erasure and maintaining dimensional control.
Solution Approach 2:
The patent introduces a depth dimension variation by making the leading shield part have a smaller depth than the substrate side shield part. The leading shield part extends only to a first depth from the medium-opposing surface, while the substrate side shield part extends to a greater second depth. This dimensional differentiation allows the leading shield to reduce erasure effects while the deeper substrate side shield maintains proper read/write separation.
2Reliability
If multiple shield layers and connecting structures are added to reduce ATE and WATE, then recording reliability improves, but manufacturing process complexity increases
Solution Approach 1:
The patent merges the leading shield part and substrate side shield part into a single continuous shield magnetic layer, connected by the linking shield part. This unified structure eliminates the need for separate manufacturing processes for multiple discrete shield components, reducing assembly steps and manufacturing complexity while maintaining the functional benefits of multiple shield regions.
Solution Approach 2:
The single shield magnetic layer structure serves multiple functions simultaneously: the leading shield part reduces ATE/WATE, the substrate side shield part maintains RWS dimension, and the linking shield part provides structural connection. This multi-functionality within a unified structure reduces manufacturing complexity compared to separate components.
3Reliability
If the leading shield part is made deeper to improve shielding effect, then ATE and WATE reduction improves, but magnetic flux leakage increases
Solution Approach 1:
The patent applies local quality by giving different depths to different parts of the shield magnetic layer. The leading shield part has a first depth optimized for reducing ATE/WATE, while the substrate side shield part has a greater second depth for maintaining RWS dimension. This localized depth variation ensures each region has the appropriate shielding characteristics for its specific function, preventing excessive magnetic flux leakage while maintaining effective shielding where needed.
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 reduces ATE and WATE, simplifies manufacturing, and maintains read/write separation within the required range, enhancing recording density and signal-to-noise ratio while increasing production efficiency.
Implementation Method 1
a thin-film coil, the thin-film coil includes a substrate side coil layer disposed between the main magnetic pole layer and the substrate
Implementation Method 2
a main magnetic pole layer having a magnetic pole end face on a side of a medium-opposing surface opposing a recording medium
Implementation Method 3
a leading shield part having a leading front end face disposed in the medium-opposing surface, and opposing the main magnetic pole layer through a nonmagnetic thin-film
Data Source
AI summary
A thin-film magnetic head is constructed such that a main magnetic pole layer, a write shield layer, a gap layer, and a thin-film coil are laminated on a substrate. The thin-film magnetic head has a leading shield part opposing the main magnetic pole layer on the substrate side of the main magnetic pole layer, a substrate side shield part has contact with the leading shield part. The thin-film coil has a substrate side coil layer between the main magnetic pole layer and substrate. The spaces to the substrate about a leading lower end face of the leading shield part, a shield upper end face of the substrate side shield part, and coil upper end face of the substrate side coil layer are formed to be equal to each other. The depth of the leading shield part is formed to be smaller than the depth of the substrate side shield part.