MEMS Microphone Back Plate Arc Transition
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Solution Overview
Problem
Existing MEMS microphones are prone to back plate breakage due to force concentration at the right-angle connection between the back plate and the substrate, leading to reduced reliability.
Innovation Solution
The MEMS microphone design includes a back plate with a middle part and a fixed part surrounding it, where the fixed part has a greater thickness and includes a first and second arc protruding from the substrate, along with an insulation layer, to distribute force more evenly and increase rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the back plate is directly connected to the substrate at right angles, then the device complexity is reduced and manufacturing is simplified, but force concentration occurs at the connection point making the back plate easy to break and reducing reliability
Solution Approach 1:
The connection part of the back plate is designed with arc-shaped surfaces instead of right angles. The first arc connects the middle part to the fixed part, and the second arc connects the first arc to the substrate, creating a curved transition that distributes stress evenly and eliminates force concentration at sharp corners.
Solution Approach 2:
The thickness of the connection part is increased compared to the middle part to enhance structural strength at the stress-prone connection region. This parameter change ensures the back plate can withstand large sound pressures without breaking while maintaining the simplified direct connection structure.
2Strength
If the thickness of the fixed part is increased to improve strength, then the back plate becomes more resistant to breakage, but the manufacturing precision requirements increase due to the multi-layer structure
Solution Approach 1:
The fixed part is constructed as a composite structure with a main body part and an insulation layer stacked together. This composite design achieves the required thickness and strength through material layering rather than requiring high-precision single-layer thickness control, thereby reducing manufacturing precision requirements while maintaining structural integrity.
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 the force distribution and increases the rigidity of the back plate, reducing the likelihood of breakage and improving the signal-to-noise ratio of the MEMS microphone.
Implementation Method 1
a capacitive system supported by the substrate and comprising a back plate and a vibration diaphragm
Data Source
AI summary
The present invention provides a MEMS microphone including a substrate with a back cavity and a capacitive system disposed on the substrate. The capacitive system includes a back plate and a vibration diaphragm arranged opposite to the back plate. The back plate includes a middle part and a fixed part surrounding the middle part and fixed to the substrate. The fixed part is arranged with a thickness greater than that of the middle part, and the fixed part includes a first surface away from the substrate and a second surface opposite to the first surface. The first surface includes a first arc connected to the middle part, and the first arc protrudes away from the substrate. Compared with related technologies, the MEMS microphone provided by the present invention can improve the reliability of the back plate.