MEMS Microphone Support Structure for Mechanical Reliability
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Solution Overview
Problem
Conventional MEMS microphones fail to meet mechanical reliability standards, particularly in air pressure and drop tests, due to the vulnerability of their anchors, leading to potential deformation and damage.
Innovation Solution
A MEMS microphone design featuring a substrate with a support structure comprising a closed-loop patterned first bracket and a second bracket connecting to the opening's periphery, which includes a square-like opening with curved corners and a specific radius, enhancing mechanical stability by distributing force and reducing stress on the electrode plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anchors are used to mount the electrode plate, then the structure is simple, but the mechanical reliability is poor and the anchors are vulnerable to damage
Solution Approach 1:
The support structure is divided into multiple components: a first bracket with closed-loop pattern and a second bracket connecting to the opening periphery. This segmentation distributes mechanical stress across multiple elements rather than concentrating it in single anchors, thereby improving reliability while maintaining manageable complexity
Solution Approach 2:
The opening is designed with curved corners instead of sharp angles, and the first bracket uses a closed-loop pattern. These curved geometries reduce stress concentration points that would otherwise exist at sharp corners, improving mechanical reliability without significantly increasing structural complexity
2Stability of the object's composition
If the opening size is equal to the electrode plate size, then the acoustic channel is efficient, but the mechanical stability is poor during transport and operation
Solution Approach 1:
The support structure adds a dimensional element by extending brackets from the opening periphery into the acoustic channel space. This allows the opening to be smaller than the electrode plate while still providing adequate acoustic passage, as the brackets create structural support without blocking the entire channel area
Solution Approach 2:
The closed-loop pattern of the first bracket and the curved corners provide localized structural reinforcement at critical stress points, while the rest of the opening maintains its acoustic function. This localized strengthening allows the overall opening to be smaller without compromising acoustic efficiency
3Strength
If sharp-cornered openings are used, then the manufacturing is simple, but the stress concentration is high leading to cracks and damage
Solution Approach 1:
The opening features curved corners with a specified radius (270-330 μm) instead of sharp angles. This curvature eliminates stress concentration points that would lead to crack initiation, significantly improving strength and resistance to cracking while remaining compatible with standard photolithography manufacturing processes
Data Source
AI summary
A microphone includes a substrate, an opening in the substrate, and a support structure in the opening. The support structure includes a first bracket formed in a closed-loop pattern and a second bracket connecting the first bracket to a periphery of the opening. The support structure in the opening increases the mechanical reliability of the microphone.