Wafer-Level MEMS Sensor Vibration Isolation
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Solution Overview
Problem
MEMS-based inertial sensors, such as gyroscopes, are sensitive to external vibrations due to mechanical coupling, leading to inaccurate measurements and increased costs from the use of external damping elements for vibration isolation.
Innovation Solution
A wafer-level encapsulation approach is used, where the sensor element is fabricated on a silicon or silicon-on-oxide wafer and suspended by micro-machined spring supports from a rigid outer portion of the sensor package, allowing direct anchoring to a mounting surface without additional decoupling structures, and utilizing high atmospheric pressure or gel materials for damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external damping elements are used to isolate MEMS sensors from vibrations, then measurement accuracy is improved, but device cost significantly increases
Solution Approach 1:
The patent combines the damping function with the sensor package structure itself. The spring supports are integrated into the package as both mechanical suspension elements and vibration isolation components, eliminating the need for separate external damping elements and reducing overall device cost while maintaining measurement accuracy
Solution Approach 2:
The spring supports act as intermediary elements between the sensor element and the rigid package structure. These springs provide mechanical coupling for electrical connections while simultaneously serving as vibration isolation mediators that decouple high-frequency vibrations from the sensitive sensor element
2Object-affected harmful factors
If spring supports are used to suspend the sensor element, then vibration decoupling is achieved, but device complexity increases
Solution Approach 1:
The spring supports perform multiple functions simultaneously: they provide mechanical suspension for the sensor element, enable electrical connections through embedded interconnects, and provide vibration isolation. This multi-functionality reduces the need for separate components and simplifies the overall package structure
Solution Approach 2:
The patent embeds electrical interconnects within the spring support structure itself. The wiring is nested inside the springs, allowing electrical connections to be made through the vibration isolation elements without requiring additional external wiring paths or complex routing structures
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 method effectively decouples the sensor from external vibrations, reducing the impact of unwanted frequencies and providing cost savings by eliminating the need for expensive damping and mounting systems, while maintaining accurate sensor output.
Implementation Method 1
a first spring supported by the rigid wafer outer body and extending into the first cavity, a second spring supported by the rigid wafer outer body and extending into the first cavity
Implementation Method 2
a spring supported sensor platform is suspended in a high atmospheric/ambient pressure which provides damping of the spring supported sensor
Implementation Method 3
the sensor is encased within a gel material. Gel materials are used for even higher damping than can be provided by high atmospheric/ambient pressure
Data Source
AI summary
In one embodiment, a sensor includes a rigid wafer outer body. A first cavity is located within the rigid wafer outer body, and a first vibration isolating spring is supported by the rigid wafer outer body and extends into the first cavity. A second vibration isolating spring is supported by the rigid wafer outer body and extends into the first cavity, and a first sensor packaging is supported by the first vibration isolating spring and the second vibration isolating spring within the first cavity.