Capacitive Switch Cantilever Stress Release

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Solution Overview

Problem

Conventional capacitive switches in communications terminals suffer from poor signal transmission quality due to the inability to release stress in metal film bridges, leading to bulging or sinking of beams and poor contact with conducting layers, resulting in signal leakage.

Innovation Solution

The capacitive switch design incorporates a first and second conductive cantilever separated by a substrate, with a coplanar waveguide structure that includes insulation and conducting layers, allowing the cantilevers to hang over or contact the conducting layer based on signal transmission, thereby releasing stress and improving reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a double-clamped beam structure is used in the capacitive switch, then the metal film bridge maintains structural integrity, but the stress generated by the metal film bridge cannot be released causing beam bulging or sinking

Engineering Contradiction:
Improvestructural integrity of metal film bridgeVSAvoidsignal transmission quality
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent divides the single double-clamped beam into two separate cantilever beams. Each cantilever beam is independently supported at one end and free at the other end. This segmentation allows stress to be released at the free ends of the cantilevers, preventing beam bulging or sinking while maintaining structural integrity through proper support design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a dynamic support structure that can adaptively respond to stress changes in the metal film bridge. The support structure includes adjustable elements that can compensate for beam deformation, maintaining optimal contact between the beam and conducting layer during operation, thus ensuring reliable signal transmission.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If the metal film bridge stress is not released, then the beam structure remains stable, but poor contact between beam and conducting layer causes signal leakage

Engineering Contradiction:
Improvebeam structure stabilityVSAvoidsignal leakage
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an intermediary support structure between the metal film bridge and the substrate. This support structure acts as a mediator that absorbs and distributes stress, preventing direct transmission of stress to the beam that would cause bulging or sinking. The intermediary structure ensures stable contact between the beam and conducting layer, eliminating signal leakage while maintaining beam stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If conventional MEMS technology is used for capacitive switch, then frequency band switching is achieved, but parasitic capacitance and insertion loss increase reducing signal transmission quality

Engineering Contradiction:
Improvefrequency band switching capabilityVSAvoidparasitic capacitance and insertion loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent employs thin film technology to create the capacitive switch structure with flexible metal film bridges and cantilever beams. The thin film design reduces the overall capacitance of the switch structure, thereby minimizing parasitic capacitance. The flexible nature of thin films allows for precise control of the switching action, reducing insertion loss while maintaining frequency band switching capability.

Inventive Principle:
Principle #30Flexible shells and thin films

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 design enhances signal transmission quality by reducing parasitic capacitance and insertion loss, ensuring reliable switching between on and off states without signal leakage.

Implementation Method 1

a coplanar waveguide arranged on the substrate, where the coplanar waveguide includes a first conductor configured to transmit an electrical signal

Methodology Applied
Scientific EffectElectromagnetic field propagation: Electromagnetic Induction

Implementation Method 2

an insulation medium layer is arranged on the first conductor

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Implementation Method 3

a conducting layer is arranged on the insulation medium layer

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2814174B1Capacitive switch, signal receiving and sending device, and manufacturing method
Publication Date: 2017.05.10 HUAWEI DEVICE CO LTD
  • EP2814174B1 patent drawingFigure 1~2
  • EP2814174B1 patent drawingFigure 3~4
  • EP2814174B1 patent drawingFigure 5

AI summary

Embodiments of the present invention provide a capacitive switch, an apparatus for transceiving a signal, and a method for manufacturing the capacitive switch. The capacitive switch includes: a first conductive cantilever, a second conductive cantilever, a substrate, and a coplanar waveguide arranged on the substrate, where the coplanar waveguide includes a first conductor configured to transmit an electrical signal and a second conductor and a third conductor that are arranged as ground wires on two sides of the first conductor; an insulation medium layer is arranged on the first conductor, and a conducting layer is arranged on the insulation medium layer; the first conductive cantilever is connected to the second conductor by using a first fixed end, and the second conductive cantilever is connected to the third conductor by using a second fixed end; and when a direct-current signal is transmitted on the capacitive switch, a first free end of the first conductive cantilever and a second free end of the second conductive cantilever contact the conducting layer. In the capacitive switch provided in this embodiment, a stress generated by a metal film bridge of the capacitive switch is released by using a cantilever separate structure, thereby ensuring transmission quality of a signal.