MEMS Microphone Diaphragm Support for High Sound Pressure
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Solution Overview
Problem
MEMS microphones suffer from diaphragm damage due to excessive deviation amplitude caused by large impact forces of sound waves.
Innovation Solution
A MEMS microphone design featuring a substrate, diaphragm, back plate, and a first support member with a convex portion supporting the diaphragm at its center, along with a second support member connecting the back plate and diaphragm, to prevent excessive movement and structural deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the diaphragm is made thin and flexible to improve sensitivity, then the sensitivity is improved, but the diaphragm becomes vulnerable to damage from large impact forces
Solution Approach 1:
The support structure is segmented into multiple connection portions (first connection portion, second connection portion, third connection portion) that are distributed around the cavity. This segmentation allows the support structure to flex and distribute impact forces across multiple points, preventing localized stress concentration that would damage a thin diaphragm while maintaining its sensitivity.
Solution Approach 2:
The support structure with its gradual width reduction and multiple connection portions acts as a pre-designed cushioning mechanism. When impact forces occur, the support structure deforms in a controlled manner, absorbing and distributing the energy before it reaches the diaphragm, thereby protecting the thin diaphragm from damage while allowing it to remain sensitive to normal sound waves.
2Stability of the object's composition
If the support structure is made rigid to prevent diaphragm deformation, then the structural stability is improved, but the diaphragm loses flexibility and sensitivity
Solution Approach 1:
The support structure is designed with dynamic characteristics through its varying width profile and multiple connection portions. The structure is rigid enough to provide overall stability and prevent excessive diaphragm displacement, but flexible enough to allow controlled deformation during vibration. The gradual width reduction creates a compliant support that adapts to vibration amplitudes while maintaining structural integrity.
Solution Approach 2:
Different portions of the support structure have different local properties. The connection portions have reduced width to provide flexibility and compliance, while the overall structure maintains sufficient rigidity for stability. This local variation in structural quality allows the diaphragm to be supported stably while retaining the flexibility needed for sensitive vibration detection.
3Object-affected harmful factors
If the diaphragm area is increased to improve sound pressure handling, then the sound pressure resistance is improved, but the deviation amplitude increases leading to damage
Solution Approach 1:
The support structure acts as an intermediary between the diaphragm and the cavity wall. It provides a compliant support that allows the diaphragm to handle increased sound pressure loads without developing excessive deviation amplitudes. The support structure absorbs and distributes the mechanical stress, enabling the diaphragm to be larger for better sound pressure handling while preventing excessive displacement that would cause damage.
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 design effectively prevents diaphragm damage by limiting excessive movement, enhances robustness, and maintains flexibility and sensitivity, ensuring the diaphragm withstands large sound pressures without deformation.
Implementation Method 1
The diaphragm and the back plate serve as two electrode plates to form a capacitor. When the diaphragm vibrates under the action of sound waves, the capacitance of the capacitor changes accordingly, so that the acoustic signal can be converted into an electrical signal
Data Source
AI summary
Provided is a MEMS microphone including: a substrate having a cavity penetrating thereon; a diaphragm supported by the substrate and covering the cavity; a back plate provided above the diaphragm, wherein a first preset gap is formed between the back plate and the diaphragm; and a first support member received in the cavity includes a support portion, a connection portion, and a convex portion. The connection portion extends from the support portion towards the substrate until being fixed to the substrate. The convex portion extends from an end of the support portion approaching the diaphragm towards the diaphragm until supporting the diaphragm. The diaphragm and the connection portion form a second preset gap along a vibration direction of the diaphragm. The diaphragm of the MEMS microphone has higher robustness and higher anti-dropping capability.