MEMS Switch Tear-Off Edge for Contact Material Deposition
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Solution Overview
Problem
Existing microelectromechanical switches face challenges in achieving precise switching behavior due to high roughness and varying contact material thickness, leading to undefined contact forces and pressures, which result in deviations in switch characteristics.
Innovation Solution
The implementation of a tear-off edge in contact arrangements reduces the deposition of contact materials at recessed surfaces, allowing for low roughness and defined material extensions, resulting in a small contact area that minimizes deviations and ensures precise switching behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If contact material is deposited on side walls and top surface of contact elements, then the contact surfaces are formed, but the thickness varies and roughness increases leading to undefined contact forces
Solution Approach 1:
The contact element side wall is segmented into a first region (lower portion) and a second region (upper portion) by a tear-off edge. The contact material is deposited only on the second region, separating the deposition area from the critical contact area. This segmentation allows uniform thickness control while maintaining ease of manufacture.
Solution Approach 2:
The harmful deposition of contact material on the first region (side wall portion) is eliminated by introducing a tear-off edge that prevents material accumulation in this area. Only the necessary deposition on the second region (contact surface area) is retained, extracting the harmful effect while preserving the useful function.
2Reliability
If contact material thickness is increased at top surface compared to side walls, then contact surfaces are formed, but stroke of motion varies and switch characteristics deviate
Solution Approach 1:
The contact element is segmented by a tear-off edge that creates a clear boundary between the first region (where material should not deposit) and the second region (where contact material is deposited). This segmentation simplifies the geometry control by providing a natural stop for material deposition, reducing variations in stroke and improving switch characteristic consistency.
3Ease of manufacture
If high roughness of contact surface at side walls is present, then contact material can be deposited, but contact location becomes undefined and motion stroke varies
Solution Approach 1:
The tear-off edge removes the harmful rough contact material deposition on the first region (side wall portion) while preserving the necessary deposition on the second region. This extraction eliminates the source of undefined contact location and motion stroke variation, allowing precise contact location definition.
Solution Approach 2:
The contact element is designed with different properties in different regions: the first region has a tear-off edge configuration that prevents material accumulation, while the second region has a flat surface optimized for contact material deposition. This local differentiation ensures smooth, well-defined contact surfaces where needed while preventing harmful roughness elsewhere.
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 enables a defined and precise switching behavior by reducing the influence of contact materials on the switching process, leading to consistent performance across switches.
Implementation Method 1
Either electroforming, physical vapor deposition (PVD) or a chemical vapor deposition (CVD) is used as a method for forming such metal-metal contacts
Implementation Method 2
Either electroforming, physical vapor deposition (PVD) or a chemical vapor deposition (CVD) is used as a method for forming such metal-metal contacts
Implementation Method 3
Either electroforming, physical vapor deposition (PVD) or a chemical vapor deposition (CVD) is used as a method for forming such metal-metal contacts
Data Source
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Figure 3A
AI summary
A MEMS switch comprises a first and a second contact arrangement having a side facing each other, the first and the second contact arrangement movable with respect to each other and configured for providing an electric contact in a first state and for not providing the electric contact in a second state. A first contact material is arranged at the side of the first contact arrangement. A second contact material is arranged at the side of the second contact arrangement. The side of the first and/or the side of the second contact arrangement comprises a recessed region and a projected region projected with respect to the recessed region, the projected region and the recessed region separated from each other by a tear-off edge. The first and/or the second contact material is arranged at the recessed region and at the projected region of the respective side. The electric contact is provided between the first and the second contact material in the projected region of the sides and not provided in the recessed region in the first state.