MEMS Circuit Breaker Switch Protection for High-Voltage Transients
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Solution Overview
Problem
MEMS switches face challenges in reliably operating between input and output terminals with large voltage differences for extended periods due to structural degradation from repeated switching operations, particularly under high voltage and current conditions.
Innovation Solution
The design incorporates a conductive beam anchored by a conductive post, with a mechanical stopper and control electrodes, allowing the beam to tilt and form conductive paths while minimizing stress and preventing arcing, enabling high voltage and current applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If MEMS switch structure is used for high voltage and high current applications, then the switching capability is improved, but the reliability deteriorates due to structural degradation from repeated switching operations
Solution Approach 1:
The conductive beam is divided into multiple segments or sections, allowing the stress from high voltage and current switching to be distributed across different regions rather than concentrated at a single point. This segmentation reduces mechanical degradation at any one location while maintaining the overall switching capability.
Solution Approach 2:
A mechanical stopper is positioned beneath the conductive beam to provide support and limit the maximum deflection during switching operations. This cushioning structure prevents excessive mechanical stress and potential damage before it occurs, thereby extending the operational life of the MEMS switch under high power conditions.
2Power
If the conductive beam is made more robust to handle higher voltages and currents, then the power handling capability is improved, but the mechanical stress and elastic deformation increase
Solution Approach 1:
The mechanical stopper provides predetermined support to the conductive beam, cushioning it against excessive deflection and stress during high power switching operations. This allows the beam to be optimized for power handling without being over-designed for maximum stress resistance.
Solution Approach 2:
The mechanical stopper provides localized support at a specific position beneath the conductive beam, creating a region of reduced stress concentration. This allows different parts of the beam to have different mechanical properties, with the supported region experiencing less stress during operation.
3Reliability
If the conductive post is positioned closer to one end of the beam, then the electrical isolation is improved, but the mechanical balance and stability are affected
Solution Approach 1:
The conductive post is intentionally positioned asymmetrically closer to one end of the conductive beam rather than at the center. This asymmetric positioning optimizes the electrical isolation between different terminals while the mechanical stopper compensates for the resulting mechanical imbalance, maintaining overall structural stability.
Solution Approach 2:
The mechanical stopper acts as an intermediary support element that compensates for the asymmetric positioning of the conductive post. By providing additional mechanical support at a strategic location, it balances the structural stability that would otherwise be compromised by the asymmetric post position needed for electrical isolation.
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 solution enhances the reliability and longevity of MEMS switches by maintaining electrical isolation and reducing mechanical stress, allowing them to handle higher voltages and currents without degradation.
Implementation Method 1
a conductive beam anchored over a substrate by a conductive post serving simultaneously as a mechanical pivot and a conductive path
Implementation Method 2
the mechanical stopper is configured to substantially suppress an elastic deformation of one or both of the conductive beam and the conductive post
Data Source
AI summary
High voltage micro-electromechanical systems (MEMS) switches are described. A MEMS teeter-totter switch connected between two terminals of a circuit breaker can include a beam coupled to an anchor on a substrate and two control electrodes, disposed on a surface of the substrate. An electrical overstress device connected between the two terminals in parallel with the MEMS teeter-totter switch may protect the MEMS teeter-totter switch when a high voltage transient signal is applied across the teeter-totter switch.