Electronic Lapping Guide Calibration for Magnetic Transducer Precision
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Solution Overview
Problem
Conventional electronic lapping guides (ELGs) for magnetic transducers lack precision in determining the desired length of structures like read sensors and poles, leading to variations that can result in non-functional transducers, necessitating additional inventory and re-fabrication.
Innovation Solution
The method involves calibrating the sheet resistance and offset of the ELG stripe, using techniques like the Van der Pauw method and windage test stripes, to accurately determine the length of the structure being fabricated, ensuring precise lapping termination and reduced variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ELG is used for lapping control, then lapping process can be performed, but manufacturing precision of stripe height and nose length deteriorates
Solution Approach 1:
The patent changes the measurement parameter from resistance-based length determination to direct optical measurement of the ELG stripe length. By measuring the actual physical length of the ELG stripe instead of inferring it from resistance values, the measurement precision is improved, which directly resolves the contradiction by providing more accurate length data for lapping control.
Solution Approach 2:
The patent replaces the electrical resistance measurement system with an optical measurement system. Instead of using electrical leads and resistance measurements to determine ELG length, the invention uses optical methods to directly measure the stripe length, thereby improving measurement precision and resolving the contradiction with manufacturing precision.
2Reliability
If conventional ELG method is used, then lapping can be performed, but variations in structure length increase leading to non-functional transducers
Solution Approach 1:
The patent implements a feedback mechanism where the actual ELG stripe length is measured optically and used to control the lapping process. By continuously monitoring the actual length and adjusting lapping accordingly, the system reduces variations in structure length and improves transducer functionality, resolving the contradiction between reliability and manufacturing precision.
Solution Approach 2:
The patent performs preliminary measurement of the ELG stripe length before and during lapping using optical methods. This preliminary action allows for better prediction and control of the final structure dimensions, reducing variations and improving both reliability and manufacturing precision.
3Measurement precision
If conventional resistance-based ELG measurement is used, then process is simple, but measurement precision deteriorates
Solution Approach 1:
The patent replaces the simple but imprecise electrical resistance measurement system with an optical measurement system. Although optical systems can be more complex, modern optical measurement techniques provide significantly improved precision for ELG length measurement, resolving the contradiction by prioritizing measurement precision while managing system complexity.
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 significantly improves the control over lapping, reducing variations in stripe height and nose length, enhancing device manufacturability and performance by ensuring structures are fabricated closer to desired specifications.
Implementation Method 1
The resistance of the conventional ELG 10 is measured during lapping of the transducer, via step 32. The current length of the conventional ELG 10 is determined based upon the resistance measured in step 32 and the sheet resistance of the conventional ELG 10
Implementation Method 2
The sheet resistance may be determined in a conventional manner using a conventional Van der Pauw pattern (not shown) which is provided on the substrate on which the magnetic transducer is to be fabricated
Data Source
AI summary
A slider includes a transducer including a magnetic structure having a front edge and a back edge. The slider further includes an electronic lapping guide (ELG) substantially coplanar with the magnetic structure and having a top edge and a bottom edge. The slider further includes a plurality of pads configured to calibrate a sheet resistance of the ELG and an offset of the ELG.