Patterned Leading Shield Geometry for PMR Writer Area Density
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Solution Overview
Problem
Current PMR write head designs focus primarily on side and trailing shields, neglecting the leading shield, which limits the achievement of higher tracks per inch (TPI) and bits per inch (BPI) capabilities essential for enhanced storage area density.
Innovation Solution
A patterned leading shield design with a notch in the lower layer, made of high damping material, is introduced to enhance magnetic flux return from the leading loop to the trailing loop, maintaining TPI and ATI while boosting BPI, by forming a notch in the LS2 layer and potentially replacing it with dielectric material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the leading shield is optimized with a patterned design and high damping material, then BPI and kilo flux change per inch are improved, but device complexity increases
Solution Approach 1:
The leading shield is divided into multiple layers (first leading shield layer and second leading shield layer) with the second layer being patterned with notches. This segmentation allows different regions of the shield to perform different functions - the first layer provides overall shielding while the patterned second layer controls magnetic flux distribution to enhance BPI without requiring complete redesign of the entire shield structure.
Solution Approach 2:
The second leading shield layer is made of high damping material specifically in regions where flux control is needed, while other portions may use different materials. The notches are strategically positioned to create local variations in magnetic properties, allowing precise control of magnetic flux return paths to improve kilo flux change per inch without affecting the entire shield uniformly.
2Productivity
If the leading shield geometry is modified to enhance trailing shield return field, then storage area density is improved, but manufacturing precision requirements increase
Solution Approach 1:
The leading shield is segmented into depositable layers that can be formed using standard thin-film deposition techniques. The notches in the second layer are created as discrete features that can be patterned using conventional photolithography and etching processes, breaking down the complex geometry into manufacturable steps rather than requiring monolithic precision machining.
Solution Approach 2:
The notch features are formed in the thickness dimension of the second leading shield layer rather than requiring lateral precision. By controlling the depth and pattern of notches through vertical deposition and etching processes, the design leverages the dimension perpendicular to the disk surface where manufacturing precision is more easily controlled compared to lateral dimensions.
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 increases BPI and kilo flux change per inch while maintaining TPI and adjacent track erasure, resulting in improved storage area density without significant tradeoffs.
Implementation Method 1
a middle (LS1) layer, and where the LS1 and LS2 layers are made of a high damping material, which provide an enhanced trailing shield return field
Data Source
AI summary
A PMR writer is disclosed with a leading shield in which a lower (LS2) layer, a middle LS1 layer, and an upper leading edge taper (LET) layer have a damping parameter≥0.04, and extend from an air bearing surface (ABS) to a first height (h1) from the ABS. The LS2 layer has a notch filled with dielectric material at the air bearing surface (ABS) that extends to a height≤h1, or may be completely replaced with dielectric material. Two notch front sides each form an angle β with the LS1 bottom surface, and two notch inner sides between the ABS and LS2 backside form angle δ with the ABS where each of β and δ is from 10 degrees to 170 degrees. Accordingly, bits per square inch performance is improved while substantially maintaining tracks per square inch capability for an overall gain in area density capability.