MEMS Microphone Spacer Design for Stress Relief
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Solution Overview
Problem
Microelectromechanical microphones face challenges in maintaining well-defined component positioning due to mechanical or thermal stresses, which can lead to deformation and affect reproducibility.
Innovation Solution
A microelectromechanical microphone design featuring a planar first and second electrode with a spacer and a displaceable membrane, where the membrane has a passage opening for the spacer, ensuring a gas exchange connection with the surroundings, and utilizing a spring arrangement and reinforcement structure to minimize stress and maintain precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If components are coupled together to form a microelectromechanical microphone, then the microphone can function, but mechanical or thermal stresses cause deformation and poor positioning
Solution Approach 1:
The microphone is divided into separate components (membrane, electrodes, spacer, housing) that are manufactured independently and then assembled. This segmentation allows each component to be optimized and manufactured with precise tolerances before assembly, reducing cumulative stress and positioning errors.
Solution Approach 2:
A spacer component is introduced as an intermediary element between the membrane and electrodes. This spacer maintains precise spacing and alignment during assembly, acting as a mechanical mediator that ensures accurate positioning while accommodating thermal expansion differences between materials.
2Ease of manufacture
If different materials with different coefficients of thermal expansion are used, then the microphone can be manufactured with available materials, but thermal stresses arise from coupling these materials
Solution Approach 1:
The design accounts for thermal expansion by allowing dimensional parameters to change with temperature. The spacer and housing are designed with compensation features that accommodate thermal expansion of different materials, transforming the thermal stress problem into a controlled dimensional change that does not affect functionality.
Solution Approach 2:
The microphone employs composite construction with different materials (membrane, electrodes, spacer, housing) each optimized for its specific function. The spacer acts as a transition element between materials with different thermal expansion coefficients, reducing thermal stress through its intermediate properties.
3Stability of the object's composition
If the space between electrodes is sealed, then component positioning is maintained, but gas pressure differences can form and affect membrane displacement
Solution Approach 1:
The gas exchange connection is implemented by extracting or opening a pathway through the housing structure. This allows the enclosed space to communicate with the external environment, equalizing pressure and eliminating gas pressure forces that would otherwise act on the membrane, while maintaining component positioning through the spacer.
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 minimizes mechanical stresses, ensures reproducible properties, and enhances the microphone's ability to accurately detect sound waves with high linearity and precision.
Implementation Method 1
a membrane (106) that is arranged in a space (R) defined between the first electrode (102) and the second electrode (104) and that is displaceable in the direction of the first electrode (102) or/and the second electrode (104)
Implementation Method 2
The space defined between the first and the second electrode, in which the membrane is arranged, has a gas exchange connection with the surroundings of the microphone
Data Source
AI summary
A microelectromechanical microphone includes a planar first electrode that is formed, at least in portions, from an electrically conductive material, a planar second electrode that is formed, at least in portions, from an electrically conductive material and that is arranged at a distance from the first electrode, a spacer that is arranged between the first electrode and the second electrode, and a membrane that is arranged in a space defined between the first electrode and the second electrode and that is displaceable in the direction of at least one of the first electrode or the second electrode. The membrane has a membrane passage opening through which the spacer extends. The space defined between the first and the second electrode, in which the membrane is arranged, has a gas exchange connection with the surroundings of the microphone.