Acceleration Sensor With Segmented Cavity To Reduce Zero-Point Drift
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Solution Overview
Problem
Existing acceleration sensors face challenges with zero-point drift and temporal changes due to environmental conditions and the use of inexpensive thermosetting resin packaging, which affects reliability and accuracy, especially in harsh environments.
Innovation Solution
The acceleration sensor design incorporates a Silicon On Insulator (SOI) substrate with through electrodes acting as posts to connect the mass and detection electrodes, providing mechanical and electrical stability, and using differential detection to minimize the impact of thermosetting resin deformation and environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermosetting resin packaging is used to reduce cost, then manufacturing cost is reduced, but zero-point drift and temporal changes increase due to resin deformation
Solution Approach 1:
The cavity is divided into multiple regions by forming partition walls that extend from the support substrate toward the cap layer. This segmentation creates isolated chambers that prevent uniform deformation of the entire cavity, thereby reducing the impact of thermosetting resin shrinkage on the mass and detection electrodes while maintaining cost-effective packaging.
Solution Approach 2:
The partition walls are strategically positioned to provide localized structural support in critical areas of the cavity. By concentrating reinforcement where deformation would most affect sensing accuracy, the design maintains reliability in key regions while allowing the overall structure to remain compatible with inexpensive thermosetting resin packaging.
2Device complexity
If the cavity structure is simplified for cost reduction, then manufacturing complexity is reduced, but deformation resistance due to environmental changes deteriorates
Solution Approach 1:
The cavity is divided into multiple regions by forming partition walls that extend from the support substrate toward the cap layer. This segmentation creates isolated chambers that prevent uniform deformation of the entire cavity, thereby reducing the impact of thermosetting resin shrinkage on the mass and detection electrodes while maintaining cost-effective packaging.
Solution Approach 2:
The cavity structure combines the support substrate, cap layer, and partition walls to form a composite structure. This multi-component design provides enhanced deformation resistance compared to a simple single-layer cavity, while still being compatible with inexpensive thermosetting resin packaging methods.
3Measurement precision
If the mass is allowed to move freely for accurate acceleration detection, then measurement precision is improved, but sensitivity to environmental distortion increases
Solution Approach 1:
The cavity is divided into multiple regions by forming partition walls that extend from the support substrate toward the cap layer. This segmentation creates isolated chambers that prevent uniform deformation of the entire cavity, thereby reducing the impact of thermosetting resin shrinkage on the mass and detection electrodes while maintaining cost-effective packaging.
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 results in a highly reliable acceleration sensor with reduced zero-point drift and temporal changes, maintaining accuracy even in poor installation environments and with inexpensive thermosetting resin packaging.
Implementation Method 1
measures acceleration by detecting a physical quantity associated with an inertial force generated in a vibrating object
Implementation Method 2
a detection electrode together with the mass forming electrostatic capacitance
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Provided is a highly reliable acceleration sensor having little 0-point drift. For example, an acceleration sensor having a support substrate having a first direction and a second direction orthogonal thereto in a single surface, a device layer disposed on the support substrate with a space interposed therebetween and having a weight that deforms according to the application of acceleration, and a cap layer disposed on the device layer with a space interposed therebetween, wherein a fixed part fixed to the support substrate is provided in the center of the weight, a beam is provided that extends from the fixed part and makes the weight mobile by being connected thereto, a plurality of posts for coupling the support substrate and the cap layer are disposed on the fixed part, and electric signals are applied to and received from the weight via the posts.