Conductive Overlay for Head-Medium Contact Sensor Parasitic Resistance
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Solution Overview
Problem
Contact sensors in data storage systems face performance issues due to high parasitic resistance, which reduces the signal-to-noise ratio (SNR) and affects the accuracy of thermal asperities, head-medium spacing, and head temperature sensing.
Innovation Solution
The implementation of a contact sensor with an electrically conductive overlay that reduces parasitic resistance by increasing the effective cross-sectional area of leads while minimizing heat transfer to the sensor element, optimizing the overlay's coverage to balance resistance reduction and heat sinking prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the cross-sectional area of leads is increased to reduce parasitic resistance, then the signal-to-noise ratio is improved, but heat transfer to the sensor element increases
Solution Approach 1:
The lead structure is segmented into two distinct parts: an inner lead in direct thermal contact with the sensor element, and an outer lead shield that is thermally isolated from the sensor. This segmentation allows the outer lead to have a larger cross-sectional area for reduced parasitic resistance without increasing heat transfer to the sensor element, as the thermal path is blocked by the low thermal conductivity barrier layer.
Solution Approach 2:
A barrier layer with low thermal conductivity is introduced as an intermediary between the inner lead and the outer lead shield. This intermediary layer acts as a thermal insulator, preventing heat from the outer lead from reaching the sensor element while allowing the outer lead to provide electrical conduction with reduced resistance.
2Measurement precision
If an electrically conductive overlay is added to increase effective cross-sectional area of leads, then parasitic resistance is reduced, but device complexity increases
Solution Approach 1:
The overlay is merged with the lead structure such that it forms an integrated conductive assembly. The overlay is electrically connected to the lead and extends beyond it, creating a combined structure that increases the effective cross-sectional area for current flow without requiring separate independent components. This merging approach reduces the number of discrete parts and simplifies the overall device architecture.
Solution Approach 2:
The overlay serves multiple functions simultaneously: it increases the effective cross-sectional area to reduce parasitic resistance, provides structural support to the lead assembly, and can be designed to extend beyond the lead to provide additional thermal isolation or mechanical protection. This multi-functionality reduces the need for separate components and simplifies the overall device design.
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 signal-to-noise ratio (SNR) and improves the accuracy of thermal sensing, maintaining consistent performance across varying conditions by effectively managing parasitic resistance and heat transfer.
Implementation Method 1
An electrically conductive overlay covers a portion of the peripheral wings and at least a portion of the leads
Implementation Method 2
contact sensor provided at or near an air bearing surface of a slider and having a temperature coefficient of resistance
Data Source
AI summary
A contact sensor is provided at or near an air bearing surface of a slider and having a temperature coefficient of resistance. The contact sensor is coupled to a lead arrangement comprising a first lead and a second lead. The contact sensor comprises a sensor element, a first peripheral wing comprising an inner wing connected to the sensor element and an outer wing connected to the first lead, and a second peripheral wing comprising an inner wing connected to the sensor element and an outer wing connected to the second lead. An electrically conductive overlay covers at least the outer wings of the first and second peripheral wings and some or all of the first and second electrical leads.