Read Transducer Wear Layer for CPP Sensor Protection
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Solution Overview
Problem
Magnetic tape heads with current-perpendicular-to-plane (CPP) reader transducers are susceptible to electrical shorts due to scratches and smearing from abrasive particles, leading to reduced sensitivity and data track loss in tape storage systems.
Innovation Solution
Incorporating dielectric layers into the shields of the read transducer structure, which extend into the shields from the media-facing surface, provides magnetic continuity and protects against shorting, enhancing the reliability of CPP sensors like TMR readers by separating the sensor and shields, thus preventing conductive material smearing and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the spacing between the magnetic head and the magnetic tape is minimized to improve data reading sensitivity, then the read elements can be in near contact with the tape for effective magnetic field coupling, but the sensor becomes susceptible to scratching and electrical shorts from abrasive particles on the tape surface
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the sensor and the tape surface. This dielectric layer extends into the shield from the media-facing surface, creating a protective barrier that prevents direct contact between abrasive tape particles and the sensor structure, thereby eliminating electrical shorts while preserving magnetic field coupling
Solution Approach 2:
The dielectric layer serves as a pre-established protective cushion that absorbs and distributes mechanical stresses from tape asperities before they can reach the sensor. This beforehand protection prevents deformation of conductive materials and electrical shorts during tape passage
2Reliability
If a protective layer is added between the sensor and the tape to prevent scratching and shorting, then the sensor reliability improves, but the spacing between the sensor and the tape increases causing spacing loss
Solution Approach 1:
The dielectric layer extends into the shield from the media-facing surface rather than being a simple planar layer between sensor and tape. This three-dimensional configuration allows the protective function to be achieved while minimizing the spacing increase, as the layer utilizes the shield volume rather than adding linear distance from the tape surface
3Reliability
If the dielectric layer extends deeply into the shield to maximize protection, then the anti-shorting capability improves, but the magnetic continuity of the shield is compromised
Solution Approach 1:
The dielectric layer is positioned locally at the media-facing surface and extends partially into the shield only where needed for protection. The shield structure maintains its magnetic continuity in the regions where the dielectric layer does not intrude, allowing different parts of the shield to have different functional properties: protected at the surface, magnetically continuous in the bulk
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 dielectric layers in the shields reduce the likelihood of electrical shorts, maintaining sensor sensitivity and allowing for closer proximity to the media without significant spacing loss, thereby improving data reading reliability and reducing wear-related issues in tape heads.
Implementation Method 1
A dielectric layer extends into one of the shields from the media facing surface
Implementation Method 2
The upper and lower shields providing magnetic shielding
Implementation Method 3
A current-perpendicular-to-plane sensor is positioned between the upper and lower shields
Data Source
AI summary
In one general approach, an apparatus includes a read transducer structure having a media facing surface. The read transducer structure has a lower shield, and an upper shield formed above the lower shield. The upper and lower shields providing magnetic shielding. A current-perpendicular-to-plane sensor is positioned between the upper and lower shields. A dielectric layer extends into one of the shields from the media facing surface. The dielectric layer extends into the one of the shields for a distance that is less than a height of the one of the shields. Preferably, a first dielectric layer extends into the lower shield from the media facing surface, and a second dielectric layer extends into the upper shield from the media facing surface.