Dual-Substrate MEMS Plate Switch for Reduced Contact Resistance
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Solution Overview
Problem
Microelectromechanical systems (MEMS) switch devices, particularly electrostatic relays, face challenges with the fragility of thin moveable substrates during fabrication and the limited contact area of cantilevered designs, which can lead to damage and reduced switching efficiency.
Innovation Solution
The development of an electrostatic MEMS plate switch using dual substrates with a deformable plate supported by spring beams, allowing for a hermetic seal and multiple contact points, reducing the likelihood of arcing and enhancing switching speed by minimizing viscous squeeze film damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin moveable substrate is used to enable electrostatic deflection, then the switch can be activated with electrostatic force, but the substrate becomes delicate and susceptible to damage during fabrication and operation
Solution Approach 1:
The device is divided into two separate substrates: a first substrate containing the deformable plate and spring beams, and a second substrate containing the fixed electrode and contact elements. This segmentation allows each substrate to be optimized independently - the first substrate can be thin enough for electrostatic actuation while the second substrate provides structural support and protection.
Solution Approach 2:
The thicker second substrate acts as a protective cushion for the fragile first substrate. During fabrication, handling, and operation, the robust second substrate shields the delicate thin substrate from mechanical damage, allowing the thin substrate to perform its electrostatic function without being vulnerable to external forces.
2Reliability
If a cantilevered beam design is used, then the switch structure is simple, but the contact area is limited which reduces switching efficiency and increases arcing tendency
Solution Approach 1:
The invention transitions from a one-dimensional cantilevered beam contact to a two-dimensional plate contact. The deformable plate can move toward the fixed electrode in the vertical dimension while maintaining a large horizontal contact area, effectively adding dimensional capability to increase contact surface area without complicating the basic beam structure.
Solution Approach 2:
The contact geometry parameters are changed from a narrow beam tip to a broad plate surface. By increasing the surface area parameter of the contact interface, the current density is reduced, arcing is minimized, and switching efficiency is improved while maintaining the simplicity of the electrostatic actuation mechanism.
3Adaptability or versatility
If multiple switch contacts are placed on a single deformable plate, then the device integrates multiple functions, but the plate structure becomes more complex
Solution Approach 1:
The deformable plate is designed as a universal structure that can accommodate multiple contact points and configurations. By creating a versatile plate design that can serve multiple switching functions simultaneously, the invention achieves multi-contact capability without proportionally increasing structural complexity, as the same basic plate and spring beam architecture supports multiple contacts.
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 dual substrate design improves the durability and switching efficiency of MEMS switches by providing a robust structure and reducing contact resistance, enabling operation from DC to 10 GHz with actuation voltages between 35-50V, while maintaining a compact form factor.
Implementation Method 1
Upon applying a voltage between the moveable electrode and the fixed electrode, the moveable substrate is attracted to the fixed substrate such that an electrode provided on the moveable substrate contacts another electrode provided on the fixed substrate to close the microrelay.
Implementation Method 2
a first, lower substrate on which to form a deformable plate with at least one electrical shunt bar
Data Source
AI summary
Systems and methods for forming an electrostatic MEMS plate switch include forming a deformable plate on a first substrate, forming the electrical contacts on a second substrate, and coupling the two substrates using a hermetic seal. The deformable plate may have a flexible shunt bar which has one end coupled to the deformable plate, and the other end coupled to a contact on the second substrate. Upon activating the switch, the deformable plate urges the shunt bar against a second contact formed in the second substrate, thereby closing the switch. The hermetic seal may be a gold/indium alloy, formed by heating a layer of indium plated over a layer of gold. Electrical access to the electrostatic MEMS switch may be made by forming vias through the thickness of the second substrate.