Magnetic Head Substructure Composite Sensor Lapping Control
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Solution Overview
Problem
Conventional methods of manufacturing magnetic heads face challenges in achieving uniform neck height and other parameters, leading to variations in write characteristics, particularly in high-density recording systems, which result in reduced yield and increased defects in magnetic heads.
Innovation Solution
A method involving the use of multiple sensors to monitor and control various parameters such as neck height and track width, where these sensors are electrically connected to form a composite sensor, allowing for precise lapping of medium facing surfaces to achieve predetermined values, thereby improving the yield of magnetic heads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the neck height is reduced to improve overwrite property, then overwrite capability improves, but effective track width increases causing adjacent track erasing and unwanted writing
Solution Approach 1:
The patent employs sensors that detect the actual neck height during the lapping process and provides feedback to the control system. The control system adjusts the lapping amount in real-time based on this feedback to achieve the target neck height, thereby optimizing overwrite capability while preventing adjacent track erasing through precise control.
Solution Approach 2:
The patent replaces conventional mechanical measurement methods with optical sensors to measure neck height. This substitution enables non-contact, high-precision measurement during lapping, allowing for accurate control of neck height without mechanical interference, thus achieving the optimal balance between overwrite property and track width control.
2Ease of manufacture
If conventional single-sensor lapping control is used to simplify the process, then manufacturing complexity is reduced, but variations in neck height and other parameters occur leading to reduced yield
Solution Approach 1:
The patent combines multiple sensors (including neck height sensors and track width sensors) into an integrated sensing system. These sensors work together to simultaneously monitor multiple parameters during lapping, enabling comprehensive control of various geometric parameters and ensuring uniformity across magnetic heads while maintaining a coordinated manufacturing process.
Solution Approach 2:
The patent develops a multi-functional sensing and control system that can simultaneously measure and control multiple parameters (neck height, track width, etc.) during a single lapping operation. This universal system replaces multiple separate control processes, achieving high precision parameter control without significantly increasing manufacturing complexity.
3Reliability
If multiple parameters are controlled simultaneously to ensure consistent write characteristics, then write head performance is improved, but the complexity of the lapping control system increases
Solution Approach 1:
The patent segments the control task by assigning specific functions to different sensors and control modules. Each sensor monitors a specific parameter (neck height, track width), and each control module processes the corresponding data independently. This segmentation allows simultaneous control of multiple parameters while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
The patent introduces a central control system that acts as an intermediary between multiple sensors and the lapping mechanism. This intermediary coordinates the data from various sensors and generates unified control signals, enabling simultaneous control of multiple parameters while simplifying the overall system architecture through centralized management.
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 enhances the yield of magnetic heads by ensuring that multiple parameters influencing write characteristics are accurately controlled, reducing variations and improving the overwrite property and effective track width, thus addressing the issues of adjacent track erasing and unwanted writing.
Implementation Method 1
a surface formed in each head aggregate by cutting the substructure is lapped to thereby form the medium facing surfaces of the pre-head portions included in each head aggregate
Data Source
AI summary
A substructure in which a plurality of pre-head portions are aligned in rows is to be cut later so that the pre-head portions are separated from one another. A surface formed by cutting the substructure is lapped to form medium facing surfaces. The substructure includes a plurality of sensors that respectively show individual sensor values corresponding to values of a plurality of different parameters each of which has an influence on characteristics relating to the pole layer and each of which depends on the position of the medium facing surface. The individual sensor values are resistance values each of which varies according to the position of the medium facing surface. The plurality of sensors are electrically connected to each other to form a composite sensor that shows a composite sensor value, which is a resistance value that depends on the resistance values of the plurality of sensors.