Magnetic Transducer Coil Stacking for High Data Rate Recording
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Solution Overview
Problem
Conventional magnetic recording transducers face challenges in achieving higher data rates due to limitations in yoke length and thermal protrusions, which affect flux conduction and coil insulation, making them unsuitable for high-data-rate applications.
Innovation Solution
A magnetic transducer design with a write pole and coil configuration featuring turns with varying lengths in the stripe height direction, utilizing a low coefficient of thermal expansion insulator like aluminum oxide to maintain a smooth dome shape and reduce thermal protrusions, while allowing for a shorter yoke length and improved response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the yoke length is reduced to enable faster flux reversals, then the response time is improved, but the coil cross-section area is reduced making it difficult to support desired current and provide sufficient insulation
Solution Approach 1:
The patent transitions from planar coil winding to a three-dimensional stacked configuration where multiple coil layers are positioned at different heights above the pole tip. This vertical stacking allows the coil to achieve sufficient cross-sectional area and insulation volume within a shortened yoke length, resolving the contradiction between fast response time and adequate coil dimensions.
Solution Approach 2:
Multiple coil layers are nested vertically one above another, with each layer contributing to the overall magnetic field generation. This nesting approach maximizes the effective coil cross-section within the constrained yoke length, providing both sufficient current support and insulation volume without extending the yoke length.
2Ease of manufacture
If photoresist is used as the insulator, then the manufacturing process is simplified, but thermal protrusions occur due to the large coefficient of thermal expansion
Solution Approach 1:
The patent changes the material parameter of the insulator from photoresist to alumina, which has a significantly lower coefficient of thermal expansion. This material substitution eliminates thermal protrusions while maintaining manufacturing feasibility through conformal deposition processes, resolving the contradiction between ease of manufacture and thermal stability.
Solution Approach 2:
The patent employs a composite structure where alumina insulator material is conformally deposited over the coil turns. This composite approach combines the electrical insulation properties of ceramic materials with the structural requirements of the transducer, providing thermal stability without sacrificing manufacturability.
3Ease of manufacture
If the shield is conformal with a wiggly insulator surface, then the fabrication process is simplified, but the flux conduction is adversely affected at high data rates
Solution Approach 1:
The patent extracts and removes the wiggly surface features from the insulator structure by using a smooth-domed shield that overhangs the coil turns. This eliminates the flux-conducting path disruptions caused by surface irregularities, ensuring reliable high-data-rate performance while maintaining simplified fabrication through conformal deposition.
Solution Approach 2:
Instead of making the shield conformal to the wiggly insulator surface, the patent inverts the approach by creating a smooth-domed shield that overhangs the coils. This reverse geometry eliminates the harmful surface effects while preserving the ease of manufacture through standard conformal deposition techniques.
4Ease of manufacture
If a two-piece shield is used, then the fabrication flexibility is improved, but a permanent pole tip protrusion is created
Solution Approach 1:
The patent merges the shield into a single-piece structure with a smooth dome shape that overhangs the coil turns. This unified structure eliminates the permanent pole tip protrusion created by two-piece shields while maintaining fabrication flexibility through conformal deposition processes, resolving the contradiction between manufacturing ease and geometric precision.
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
The design enhances performance at high data rates by reducing yoke length, improving response time, and minimizing thermal protrusions, enabling more efficient flux conduction and fabrication simplicity.
Implementation Method 1
The coil energizes the write pole and includes a plurality of turns
Implementation Method 2
utilizing a low coefficient of thermal expansion insulator like aluminum oxide to maintain a smooth dome shape and reduce thermal protrusions
Data Source
AI summary
A method and system provide a magnetic transducer having an air-bearing surface (ABS). The magnetic transducer includes a write pole and a coil. The write pole has a pole tip and a yoke. The coil energizes the write pole and includes a plurality of turns. A turn of the plurality of turns has a first portion and a second portion. The first portion has a first length in a stripe height direction substantially perpendicular to the ABS. The second portion has a second length in the stripe height direction. The second length is greater than the first length and extends at least to at least one adjacent turn.