GMR Sensor Corrosion Protection via Etched Back Non-Magnetic Layer
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Solution Overview
Problem
Corrosion in the non-magnetic metal layer of giant magneto-resistive sensors reduces their effectiveness and can lead to failure, with existing solutions either causing signal loss or increasing manufacturing complexity.
Innovation Solution
The non-magnetic metal layer is etched back and protected through mechanical entrainment or plating, allowing the free layer to project outward and remain at the magnetic sensor/magnetic media interface, reducing corrosion without introducing additional spacing or signal losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a giant magneto-resistance sensor is used to increase the percentage change in sensor resistance, then the signal available from the sensor is improved, but corrosion in the non-magnetic metal layer is re-introduced
Solution Approach 1:
The non-magnetic metal layer is selectively removed (etched back) from the trailing edge region of the sensor, extracting only the problematic portion that is susceptible to corrosion while preserving the functional layers needed for GMR effect operation
Solution Approach 2:
The sensor structure is segmented into different regions with different layer configurations - the leading edge maintains the complete stack for optimal signal detection, while the trailing edge has the non-magnetic metal layer removed to prevent corrosion
2Reliability
If the non-magnetic metal layer is removed to prevent corrosion, then corrosion resistance is improved, but the free layer must project outward which may affect manufacturing precision
Solution Approach 1:
The non-magnetic metal layer is etched back during the manufacturing process before final assembly, preliminarily preparing the structure to prevent future corrosion while establishing the required edge alignment between layers
Solution Approach 2:
Different regions of the sensor have different structural qualities - the free layer projects outward specifically at the trailing edge where corrosion occurs, while maintaining proper alignment and configuration in the active sensing region
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 effectively reduces corrosion in the non-magnetic metal layer while maintaining optimal magnetic performance and compatibility with various magnetic storage systems, preventing sensitivity degradation.
Implementation Method 1
The sensor's ΔR/R can be increased using the giant magneto-resistance (GMR) effect. The ΔR/R for a giant magneto-resistance sensor is about 10% to about 20%.
Implementation Method 2
The non-magnetic metal layer is etched back and protected through mechanical entrainment or plating
Implementation Method 3
The non-magnetic metal layer is etched back and protected through mechanical entrainment or plating
Data Source
AI summary
A corrosion-resistant magnetic sensor and a method for making the corrosion-resistant magnetic sensor. The magnetic sensor includes a first layer that is a pinned layer, the first layer having a first edge. The magnetic sensor also includes a second layer that can be a non-magnetic metal layer, the second layer having a second edge corresponding to the first edge, wherein the second layer is adjacent the first layer. The magnetic sensor also has a third layer that can be a free layer, the third layer having a third edge which projects outwardly relative to the first edge and the second edge.