Electro-Acoustic Transducer Membrane With Stress-Relieving Beams

Solution Overview

Problem

Existing MEMS devices used in electro-acoustic transducers face challenges in reducing stress concentrations and breakage of torsion and drive beams, which affect their performance and reliability.

Innovation Solution

The MEMS device incorporates a frame-shaped fixed portion with a movable portion connected by torsion and drive beams, featuring offset connections and specific beam shapes to reduce stress concentrations, along with a substrate design that includes a cavity to accommodate the movable portion's displacement and reduce air resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional MEMS device structures are used, then manufacturing is simplified, but stress concentrations and breakage of torsion and drive beams occur

Engineering Contradiction:

Improvebeam durabilityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by providing reinforcement structures specifically at the connection portions between beams and fixed/movable portions, rather than uniformly throughout the entire device. This targeted reinforcement reduces stress concentrations at critical locations while maintaining overall structural simplicity and manufacturing ease.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the reinforcement function from the main beam structure by introducing separate reinforcement structures at connection portions. This segmentation allows the beams to maintain their primary function while the reinforcement structures independently address stress concentration issues, improving durability without significantly complicating the overall device architecture.

Inventive Principle:

Principle #1Segmentation

2Strength

If beam thickness is increased to reduce breakage, then strength improves, but air resistance increases and resonance frequency decreases

Engineering Contradiction:

Improvebeam strengthVSAvoidresonance frequency

Core Design Contradiction:

StrengthVSSpeed

Solution Approach 1:

The patent applies local quality by providing reinforcement structures specifically at the connection portions between beams and fixed/movable portions, rather than uniformly throughout the entire device. This targeted reinforcement reduces stress concentrations at critical locations while maintaining overall structural simplicity and manufacturing ease.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The reinforcement structures act as beforehand cushioning by providing stress distribution mechanisms at connection portions before breakage can occur. These structures preemptively address potential failure points, allowing the beams to maintain optimal thickness for resonance frequency while still achieving the necessary strength through the distributed reinforcement.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If uniform bonding is applied between substrate and fixed portion, then manufacturing is simple, but stress concentrations occur at connection points

Engineering Contradiction:

Improvebonding process simplicityVSAvoidconnection reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by providing reinforcement structures specifically at the connection portions between beams and fixed/movable portions, rather than uniformly throughout the entire device. This targeted reinforcement reduces stress concentrations at critical locations while maintaining overall structural simplicity and manufacturing ease.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250310698A1Membrane and electro-acoustic transducer

Publication Date: 2025.10.02 MITSUMI ELECTRIC CO LTD

AI summary

An electro-acoustic transducer includes a substrate, a MEMS device disposed on the substrate, and a membrane disposed on the MEMS device. The electro-acoustic transducer further includes a pair of internal connection pads that serve as a path for a signal to be supplied to a drive source; and one or more height adjustment pads disposed in a region of an upper surface of the substrate that overlaps with a fixed portion in plan view. A lower surface of the fixed portion is bonded to the upper surface of the substrate, and the internal connection pads and the height adjustment pad are interposed between the substrate and the fixed portion.