Transducer Lapping Control via Disk Windage Resistance Measurement
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Solution Overview
Problem
Conventional methods for fabricating energy-assisted magnetic recording (EAMR) transducers, such as lapping, face challenges in precisely controlling the dimensions of near-field transducers (NFTs), particularly the distance between the disk portion and the air-bearing surface, due to limitations in existing electronic lapping guides (ELGs).
Innovation Solution
The implementation of lapping control and disk windage ELGs, where the lapping control ELG has edges at specific distances from the air-bearing surface and the disk windage ELG measures windage resistance to determine actual disk dimensions, allowing for adjustments to the lapping target resistance to ensure precise control during the lapping process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional ELG is used to control lapping, then the lapping process can be monitored via resistance measurement, but the NFT dimensions cannot be precisely controlled due to the ELG length decreasing during lapping
Solution Approach 1:
The patent divides the monitoring function into two separate ELGs: a lapping control ELG that monitors lapping progress and a disk windage ELG that specifically measures the disk portion dimension. This segmentation allows independent measurement of different critical dimensions without interference from mutual lapping wear, resolving the contradiction between monitoring capability and measurement accuracy.
Solution Approach 2:
The disk windage ELG acts as an intermediary measurement tool that indirectly determines the disk portion length through resistance measurement, rather than directly measuring the physical length. This intermediary approach enables precise dimension control without the measurement errors caused by conventional direct length measurement methods.
2Productivity
If the ELG length is reduced during lapping, then lapping progress can be tracked via resistance change, but the desired NFT length cannot be easily controlled to the desired length
Solution Approach 1:
The patent segments the measurement function into two independent ELGs with distinct purposes: one for monitoring lapping progress (lapping control ELG) and one for controlling disk dimension (disk windage ELG). This allows simultaneous productivity improvement through real-time monitoring while maintaining manufacturing precision through dedicated dimension control.
Solution Approach 2:
The patent uses resistance as a measurable parameter that changes predictably with ELG length. By measuring the resistance of the disk windage ELG and comparing it to a predetermined target resistance, the system can precisely control the disk portion length. The lapping process is terminated when the resistance indicates the desired dimension has been achieved.
3Device complexity
If a single ELG is used for both lapping control and disk dimension measurement, then device complexity is reduced, but measurement accuracy for disk windage deteriorates
Solution Approach 1:
The patent introduces a second ELG (disk windage ELG) specifically dedicated to measuring disk portion dimensions. Although this increases device complexity slightly, it dramatically improves measurement precision for critical dimensions by eliminating the interference and errors associated with using a single ELG for multiple purposes.
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 method enables more accurate control of NFT dimensions by measuring windage resistance and adjusting lapping target resistances, thereby improving the precision of transducer fabrication and preventing unintended lapping errors, such as overlapping or removal of disk portions.
Implementation Method 1
measuring a windage resistance of the disk windage ELG and determining a disk windage corresponding to a difference between a designed disk dimension perpendicular to the ABS and the disk dimension
Implementation Method 2
lapping the transducer and terminating the lapping based on a resistance of the lapping control ELG and the lapping ELG target resistance
Data Source
AI summary
A method and system for providing transducer(s) including a disk structure and having an air-bearing surface (ABS) are described. The disk structure resides a distance from the ABS and has a disk dimension substantially perpendicular to the ABS. Lapping control and disk windage ELGs are provided. The lapping control ELG has first and second edges first and second distances from the ABS. The disk windage ELG has edges different distances from the ABS. A difference between these edges corresponds to the disk dimension. A windage resistance of the disk windage ELG is measured and a disk windage determined. The disk windage corresponds to a difference between designed and actual disk dimensions perpendicular to the ABS. A lapping ELG target resistance is determined based on the disk windage. The transducer is lapped. Lapping is terminated based on a resistance of the lapping control ELG and the lapping ELG target resistance.