Selectable Read Sensors for Storage Device Yield and Reliability
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Solution Overview
Problem
As areal recording densities for storage discs increase, existing data storage devices face challenges in maintaining high yield and reliability due to variations in read sensor performance, leading to potential failures and reduced bit error rates.
Innovation Solution
The method involves fabricating a read head with multiple read sensors and selecting the most suitable one for operation in a data storage device based on comparative measurements, allowing for improved yield and reliability by choosing the sensor with better bit error rate and areal density capabilities, and enabling a switch to a redundant sensor if one fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple read sensors are fabricated in a read head, then reliability is improved through redundancy and selection, but device complexity increases
Solution Approach 1:
The read head is segmented into multiple independent read sensor elements (first read sensor, second read sensor) that can be independently fabricated, tested, and selected. Each sensor is a separate functional unit with its own read element, allowing individual performance evaluation and selection of the optimal sensor for operation.
Solution Approach 2:
The invention changes the parameter of sensor redundancy by fabricating multiple read sensors with potentially different geometries, materials, or operational characteristics. This allows selection based on measured performance parameters such as bit error rate, signal strength, and areal density capability to optimize reliability.
2Manufacturing precision
If read sensors are selected based on comparative measurements, then manufacturing precision is improved through optimal sensor selection, but measurement precision requirements increase
Solution Approach 1:
Performance measurements are performed on multiple read sensors during the manufacturing process before final assembly. This preliminary characterization allows selection of the optimal sensor based on measured parameters such as bit error rate and signal quality, ensuring manufacturing precision without requiring extremely high measurement accuracy during operation.
Solution Approach 2:
The invention implements a feedback mechanism where measurement results from testing multiple read sensors are used to select the optimal sensor for operation. The measurement system provides feedback on sensor performance, and this information feeds back into the selection process to ensure the best sensor is chosen for each read head.
3Reliability
If redundant read sensors are implemented, then reliability is improved through failover capability, but ease of manufacture decreases
Solution Approach 1:
Multiple read sensors are merged into a single read head assembly, sharing common structures such as the substrate, interconnect layers, and packaging. This combining approach allows redundant sensors to be manufactured together in the same fabrication process, reducing overall manufacturing complexity compared to assembling separate read heads.
Solution Approach 2:
The read head is designed with universal structures that can support multiple read sensor types or configurations. The common infrastructure (substrate, interconnects, bonding pads) serves multiple functions by accommodating different sensor geometries or materials, simplifying the manufacturing process for redundant sensors.
Data Source
AI summary
A method of forming a read head. The method includes forming first and second read sensors. A first read measurement is performed on a storage medium using the first read sensor. A second read measurement is performed on the storage medium using the second read sensor. Based on a comparison of the first and second read measurements to a predetermined quantity, either the first read sensor or the second read sensor is selected to be operational in a data storage device.