MEMS Switch Contact Member Edge Design for Sticking Failure Reduction
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Solution Overview
Problem
Conventional MEMS switches suffer from sticking failures due to inadequate restoring force, leading to instability and reliability issues, especially when the membrane or central rigid body contacts the entire surface, resulting in decreased stability.
Innovation Solution
A MEMS switch design featuring a contact member that contacts the edging portions of signal lines rather than the central part, with a supporting member made of insulating materials like SiNx or SiO2, and a moving electrode with auxiliary electrodes, which reduces the contact area and increases the restoring force by distributing the contact force away from the central part, thereby minimizing sticking failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the membrane or central rigid body contacts the entire surface of the contact member, then the contact area is increased, but the restoring force is decreased causing sticking failures
Solution Approach 1:
The patent applies local quality by making different parts of the contact structure have different functions. The contact member is designed with a specific geometric shape (convex or tapered) where the contact area is concentrated at the edging portions rather than distributed over the entire surface. This localized contact approach maintains sufficient contact area for electrical connection while preserving restoring force by avoiding broad surface contact that would create adhesion.
2Reliability
If the contact area is increased for better electrical connection, then the reliability of signal transmission is improved, but the stability of the switch is decreased due to sticking failures
Solution Approach 1:
The patent inverts the conventional approach by having the contact member contact the edging portions of the signal line rather than the central part. This inversion allows the contact area to be effectively utilized for electrical connection while the geometric shape (convex or tapered) ensures that contact occurs at points with higher restoring force, thereby improving both reliability and stability simultaneously.
3Force
If DC voltage is supplied to the fixing electrode, then the moving electrode is pulled towards the substrate by electrostatic force, but the contact force is insufficient leading to sticking failures
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the contact member (convex or tapered shape) to concentrate the electrostatic force at the edging portions of the signal line. This geometric parameter change ensures that the electrostatic force generated by the DC voltage is effectively converted into sufficient contact force at the contact points, preventing sticking failures and improving reliability.
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 modified MEMS switch achieves enhanced stability and reduced sticking failures by increasing the contact force and restoring force, allowing for reliable operation at lower voltages and minimizing contact resistance.
Implementation Method 1
When DC (direct current) voltage is supplied to the fixing electrode, the conventional MEMS switch is charged between a fixing electrode and a moving electrode. The moving electrode is pulled towards a substrate by electrostatic force.
Data Source
AI summary
A MEMS (micro electro mechanical system) switch, which includes a substrate; a fixed electrode formed on an upper side of the substrate; a signal line formed on both sides of the fixed electrode; a contact member formed on an upper side of the signal line at a distance from said fixed electrode and contacting an edging portion of the signal line; a supporting member supporting the contact member to be movable; and a moving electrode disposed on an upper side of the supporting member.