MEMS Transducer Backplate with Variable Open Area
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Solution Overview
Problem
The challenge is to enhance the signal-to-noise ratio (SNR) of capacitive transducers while maintaining the mechanical strength of the backplate, as larger through-holes increase SNR but decrease mechanical strength.
Innovation Solution
The design incorporates a backplate with a center region and peripheral regions having different percentage open areas, where the percentage open area in the center region is larger than in the peripheral regions, and gradually decreases towards the edge, along with tapered through-holes and a backplate support structure to increase mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the percentage open area defined by through-holes in the backplate is increased to improve the signal-to-noise ratio, then the signal-to-noise ratio increases, but the mechanical strength of the backplate decreases
Solution Approach 1:
The backplate is divided into a center region and peripheral regions with different percentage open areas. The center region has a larger percentage open area (50% or more) to improve signal-to-noise ratio, while the peripheral regions have smaller percentage open areas to maintain mechanical strength. This local differentiation allows each region to optimize for its specific function.
Solution Approach 2:
The backplate is segmented into multiple functional zones: a center region with high open area for acoustic performance, and peripheral regions with lower open area for structural support. This segmentation resolves the contradiction by spatially separating the competing requirements of acoustic performance and mechanical strength.
2Measurement precision
If larger through-holes are used to increase the percentage open area, then the signal-to-noise ratio improves, but the mechanical strength of the backplate decreases
Solution Approach 1:
Different regions of the backplate have different through-hole configurations. The center region uses larger through-holes or higher density to achieve 50% or more open area for improved acoustic performance, while peripheral regions use smaller through-holes or lower density to maintain structural integrity.
Solution Approach 2:
The percentage open area parameter is varied spatially across the backplate rather than being uniform. The center region maintains a high percentage open area (50% or more) while peripheral regions have lower percentages, optimizing both acoustic performance and mechanical strength through parameter differentiation.
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 configuration improves the signal-to-noise ratio while maintaining the mechanical strength of the backplate, allowing for efficient sound pressure detection and resistance to external pressures.
Implementation Method 1
A capacitive transducer has a vibrating electrode membrane that vibrates under pressure; the vibrating electrode membrane faces a backplate to which the electrode membrane is secured with an air gap
Data Source
Figure 1~2
Figure 3~4
Figure 5A
AI summary
A transducer (1) includes: a substrate (2) having a hole (21); a backplate (3) facing an opening of the hole (21); and a diaphragm (4) facing the backplate (3) with an air gap therebetween. The backplate (3) includes a backplate body, a backplate support secured to the substrate and supporting the backplate body (31), and a plurality of through-holes (33) perforating the backplate body (31); the backplate body (31) includes a center region (34) and three or more peripheral regions (35A, 35B, 35C) partially or completely surrounding the center region (34); the plurality of through-holes (33) defines a percentage open area in each of the center region (34) and the three or more peripheral regions (35A, 35B, 35C), and the percentage open areas are mutually different; the percentage open area in the center region (34) is larger than the percentage open area in each of the three or more peripheral regions (35A, 35B, 35C); and the percentage open area in the outermost peripheral region (35C) of the backplate body is smaller than the percentage open area in the peripheral region (35A) near the center region.