MEMS Switch With Mechanical Biasing For Voltage-Free Operation

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Solution Overview

Problem

Conventional MEMS switches require electrical voltage to switch contacts, limiting their compatibility with CMOS technology and making them unsuitable for applications where switches should be in the normal state without voltage, and manufacturing challenges prevent reversible separation of contacts.

Innovation Solution

A MEMS switch with a mechanically prestressed bending element, using a biasing element like a layer under tensile or compressive stress, allows the switch to be in a contact position without voltage, enabling it to operate like CMOS switches and be manufactured using known semiconductor materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional MEMS switches use a bending element that requires electrical voltage to switch contacts, then the switching function is achieved, but the switch cannot operate in a normal state without voltage like CMOS switches

Engineering Contradiction:
Improvecompatibility with CMOS technologyVSAvoidelectrical voltage requirement
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the fundamental operating parameter of the MEMS switch from voltage-driven to mechanically prestressed. By introducing a biasing element that applies mechanical prestress to the bending element, the switch contacts are forced together without electrical voltage, enabling the switch to operate in a normal closed state similar to CMOS technology

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the electrical actuation mechanism with a mechanical prestressing system. Instead of using electrical voltage to deflect the bending element and close contacts, a biasing element (such as a spring or prestressed layer) mechanically forces the contacts together, eliminating the need for continuous electrical power

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If the switching contact and mating contact are already in contact during final process step, then the switch is in contact position, but the contacts stick or alloy together during high temperature processing

Engineering Contradiction:
Improvecontact position accuracyVSAvoidreversible separation of contacts
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by introducing the biasing element and mechanical prestress before the final wafer joining process. The bending element is pre-configured with a biasing mechanism that will force contacts together after release, allowing the contacts to be separated during manufacturing and then reliably closed through mechanical prestress rather than relying on precise initial positioning

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces dynamic capability to the contact system through the biasing element. Instead of rigid fixed contacts, the mechanical prestress system allows the bending element to dynamically adjust and force contacts together, ensuring reliable contact closure even after high-temperature processing that might otherwise cause sticking or alloying

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If conventional MEMS switches use metallic and/or silicon-based bending elements, then the switching function is achieved, but they cannot be manufactured in a contact position with reversible separation

Engineering Contradiction:
Improvemanufacturing process compatibilityVSAvoidcontact position flexibility
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent employs composite material structures by combining the traditional metallic or silicon-based bending element with an additional biasing element or prestressed layer. This composite approach allows the bending element to maintain its electrical and mechanical properties while the added biasing component provides the necessary mechanical prestress to force contacts together, enabling both manufacturability and contact position flexibility

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent segments the switching mechanism into distinct functional components: the bending element (which provides structural support and electrical connectivity) and the biasing element (which provides mechanical prestress). This segmentation allows each component to be optimized independently and manufactured using compatible processes, while the assembly achieves the desired contact-closed state through the combined action of both elements

Inventive Principle:
Principle #1Segmentation

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

Enables MEMS switches to function in a normal state without electrical voltage, allowing for reversible separation of contacts and compatibility with CMOS technology, enhancing their operational flexibility and manufacturing feasibility.

Implementation Method 1

the bending element is mechanically prestressed into the contact position

Methodology Applied
Scientific EffectMechanical stress: Stress Relaxation

Implementation Method 2

using a biasing element like a layer under tensile or compressive stress

Methodology Applied
Scientific EffectTensile stress: Tension

Implementation Method 3

using a biasing element like a layer under tensile or compressive stress

Methodology Applied
Scientific EffectCompressive stress: Compression

Data Source

PatentEP3929960A1MEMS switch, method of manufacturing a MEMS switch and device
Publication Date: 2021.12.29 ROBERT BOSCH GMBH
  • EP3929960A1 patent drawingFigure 1~3
  • EP3929960A1 patent drawingFigure 4~6
  • EP3929960A1 patent drawingFigure 7~9

AI summary

MEMS switch (1) with a bending element (150) and a switching contact (120) arranged on the bending element, as well as with a mating contact (250), wherein the bending element (150) can assume a contact position in which the switching contact (120) is in contact with the mating contact (250), and wherein the bending element (150) is biased into the contact position. In the method for manufacturing such a MEMS switch (1, 300), the bending element (150) is biased into the contact position.