In-situ TMR Sensor Annealing via Joule Heating
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Solution Overview
Problem
TMR sensors in magnetic storage systems face intrinsic and extrinsic breakdown issues due to stress voltages, leading to resistance drops, and traditional annealing methods are time-consuming and costly, especially for tape drive systems where the head assembly's design is complex.
Innovation Solution
Applying a current to a lead of a TMR sensor to induce Joule heating, sufficient to anneal the magnetic layer, while maintaining the current for an appropriate duration to reverse degradation without damaging other components, thus minimizing magnetic fields and voltage differential across the oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional annealing methods are used to anneal TMR sensors, then the sensor degradation can be reversed, but the process is time-consuming and costly
Solution Approach 1:
The TMR sensor anneals itself by utilizing the Joule heating effect from its own operating current. The sensor stack generates the necessary heat internally through resistive heating during normal operation, eliminating the need for external annealing equipment and processes. This self-service approach reverses sensor degradation while reducing manufacturing complexity and time
Solution Approach 2:
The patent changes the operational parameters of the TMR sensor by applying elevated current levels during a controlled time period to induce Joule heating. By modifying the current parameter and maintaining it for a specific duration, the sensor reaches temperatures sufficient for annealing without requiring external heating mechanisms, thus resolving the contradiction between effectiveness and time/cost efficiency
2Reliability
If external heating is used to anneal TMR sensors, then annealing can be achieved, but the system complexity and manufacturing cost increase
Solution Approach 1:
The TMR sensor anneals itself by utilizing the Joule heating effect from its own operating current. The sensor stack generates the necessary heat internally through resistive heating during normal operation, eliminating the need for external annealing equipment and processes. This self-service approach reverses sensor degradation while reducing manufacturing complexity and time
Solution Approach 2:
The TMR sensor stack serves dual functions: it performs its primary sensing function and simultaneously acts as its own annealing heating element. The same structural components that constitute the sensor also generate the heat required for annealing, eliminating the need for separate heating mechanisms and reducing overall system complexity
3Productivity
If high current is applied to anneal the sensor quickly, then annealing time is reduced, but excessive heat may damage other components
Solution Approach 1:
The Joule heating effect concentrates thermal energy specifically within the TMR sensor stack where resistance is highest, creating localized heating that reaches annealing temperatures only in the target component. This localized quality of heating allows rapid annealing of the sensor without subjecting surrounding components to excessive temperatures, resolving the contradiction between annealing speed and thermal damage prevention
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 effectively anneals TMR sensors in situ, reversing degradation without external heating, thereby improving sensor performance and reducing manufacturing costs and time by generating annealing heat within the tape drive system.
Implementation Method 1
a current applied to the first lead at a predetermined level when the second lead is coupled to the ground induces joule heating of the first lead or a heating layer coupled to the first and second leads
Implementation Method 2
the joule heating applied for a predetermined amount of time being sufficient to anneal a magnetic layer of the sensor
Data Source
AI summary
A computer program product according to one embodiment includes a computer readable storage medium having program instructions embodied therewith. The program instructions area executable by a data processing system having at least one processor to cause the data processing system to apply, by the data processing system, a current to a lead of a tunneling magnetoresistance (TMR) sensor for inducing joule heating of the lead or a heating layer, the level of joule heating being sufficient to anneal a magnetic layer of the sensor; and maintain, by the data processing system, the current at the level for an amount of time sufficient to anneal the sensor.