Bootstrap Band Servo Patterns for Planarization Compatibility
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Solution Overview
Problem
Conventional planarization methods struggle with filling large depressions in patterned magnetic disks due to varying shapes and sizes of servo patterns, leading to unreliable head-disk interfaces and increased manufacturing costs.
Innovation Solution
The implementation of a bootstrap band with narrow, DC magnetized servo patterns that allow for subsequent servo data writing, using liquid-based planarization to fill nonmagnetic grooves outside the band, ensuring compatibility with various planarization methods and maintaining a reliable air bearing surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional servo patterns with varying shapes and sizes are used, then servo data can be created, but planarization becomes difficult and head-disk interface reliability deteriorates
Solution Approach 1:
The servo pattern is segmented into two distinct parts: a bootstrap band with uniform-width nonmagnetic grooves for planarization, and outer servo sectors with variable-shaped patterns for data storage. This segmentation allows each part to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different regions of the disk are assigned different groove width characteristics. The bootstrap band region has uniform groove widths optimized for liquid planarization, while the servo sector regions have variable groove widths and shapes optimized for servo data patterns. This local differentiation resolves the contradiction between planarization quality and servo functionality.
2Ease of manufacture
If liquid-based planarization is used to fill nonmagnetic grooves, then planarization can be achieved, but groove width must be limited by design rules
Solution Approach 1:
The disk structure is divided into a bootstrap band with uniform grooves for planarization and servo sectors with variable grooves for data storage. This segmentation allows the uniform groove region to satisfy liquid planarization design rules while the variable groove regions maintain flexibility for different servo patterns.
Solution Approach 2:
The bootstrap band with uniform grooves is created first to enable successful liquid planarization. After planarization fills these uniform grooves, the process can then accommodate the more complex variable-width grooves in the servo sectors without compromising overall planarization quality.
3Ease of manufacture
If dry planarization is used, then planarization can be achieved, but the ratio of magnetic land widths to nonmagnetic groove widths must be constant
Solution Approach 1:
The disk is segmented into a bootstrap band with constant land-to-groove width ratios for dry planarization compatibility, and servo sectors with variable ratios for pattern flexibility. This allows both planarization methods to work effectively on their respective regions.
Solution Approach 2:
Different land-to-groove width ratio characteristics are applied locally: constant ratios in the bootstrap band for dry planarization, and variable ratios in servo sectors for pattern diversity. This local quality differentiation resolves the contradiction between manufacturability and precision.
4Ease of manufacture
If uniform groove widths are maintained everywhere, then planarization is easier, but servo pattern variety is limited
Solution Approach 1:
The disk structure separates uniform-width grooves in the bootstrap band (for easy planarization) from variable-width grooves in servo sectors (for efficient servo pattern creation). This segmentation allows both uniformity where needed and variety where required.
Solution Approach 2:
Uniform grooves are created in the bootstrap band first to facilitate planarization. Subsequently, the servo sectors can be patterned with variable groove widths and shapes without affecting the already-planarized bootstrap region, enabling efficient servo pattern creation.
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 approach enables efficient and cost-effective creation of servo patterns compatible with different planarization methods, facilitating reliable head-disk interfaces and reducing manufacturing costs by leveraging capillary forces for planarization and UV curing for stability.
Implementation Method 1
liquid-based planarization to fill nonmagnetic grooves outside the band, ensuring compatibility with various planarization methods and maintaining a reliable air bearing surface
Implementation Method 2
leveraging capillary forces for planarization and UV curing for stability
Data Source
AI summary
Embodiments herein illustrate patterned servo data that is used to facilitate subsequent servo writing to a magnetic disk while allowing the patterned disk to be planarized with a relatively simple planarization process. One disk drive system includes a magnetic disk that is patterned with magnetic lands and nonmagnetic grooves. The magnetic disk also includes bootstrap bands that may be configured at an inner diameter of the magnetic disk. The magnetic lands of the bootstrap bands have varying sizes and are patterned as servo data having a uniform polarity of magnetization. The bootstrap bands have a width that is sufficiently narrow to support an air bearing surface of a slider. The data tracks are circumferentially configured proximate to the bootstrap bands. The slider reads the patterned servo data to facilitate writing of additional servo data in the data tracks.