MEMS Inertial Sensor Lid Structure for Impact-Limited Displacement
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Solution Overview
Problem
Existing MEMS devices face damage due to excessive impact from large gaps between movable electrodes and stoppers, leading to ineffective detection of physical quantities like acceleration.
Innovation Solution
The MEMS device design incorporates a lid with an abutting part that regulates displacement, reducing the gap between the movable member and the abutting part, thereby minimizing impact and damage during displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stopper is provided on the base to regulate displacement of the movable electrode, then displacement regulation is achieved, but a large space (gap) exists between the movable electrode and the stopper due to manufacturing process restrictions, leading to excessive collision and damage when impact is applied
Solution Approach 1:
The stopper function is relocated from the base (lower dimension) to the lid (upper dimension), changing the spatial arrangement. The lid with abutting part is positioned above the movable electrode, creating a more compact vertical arrangement that reduces the horizontal gap while maintaining displacement regulation functionality.
Solution Approach 2:
The stopper function is copied and implemented as an abutting part on the lid, which regulates displacement in the in-plane direction. This creates a redundant displacement control mechanism that works complementarily with the base stopper, allowing for reduced gaps while maintaining regulatory function.
2Ease of manufacture
If the movable electrode and stopper are integrated together, then manufacturing is simplified, but the space (gap) between them increases, leading to excessive impact when displacement occurs
Solution Approach 1:
The device is segmented into distinct components: the base with support part, the movable member, and the lid with abutting part. This segmentation allows each component to be optimized independently - the lid can be positioned closer to the movable member while maintaining the same manufacturing advantages of modular assembly.
Solution Approach 2:
The abutting part is positioned in a different spatial dimension (on the lid above the movable member) rather than being integrated in the same plane. This dimensional separation enables reduced gap distances while maintaining manufacturing simplicity through modular component assembly.
3Ease of manufacture
If a large gap exists between the movable electrode and the stopper, then manufacturing constraints are satisfied, but excessive collision occurs between the movable electrode and stopper when impact is applied, causing damage
Solution Approach 1:
The lid with abutting part is positioned beforehand to create a cushioning effect that limits the travel distance of the movable member. This pre-positioned structural element prevents excessive collision by providing early contact that stops further displacement before significant impact forces can develop.
Solution Approach 2:
The displacement regulation is achieved in a different dimension by using the lid structure above the movable member rather than a distant stopper on the base. This dimensional change allows for shorter gap distances that provide better impact protection while remaining compatible with manufacturing processes.
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 enhances the reliability of MEMS devices by reducing damage to both the movable member and the abutting part, allowing for secure regulation of displacement and continuous measurement of physical quantities.
Implementation Method 1
The movable electrode swings in response to a physical quantity such as acceleration applied to the MEMS device, thus changing the space between movable electrode and the detection electrode. The MEMS device detects the physical quantity such as acceleration applied to the MEMS device, based on a change in the electrostatic capacitance generated between the two electrodes according to the change in the space.
Implementation Method 2
The lid has an abutting part which faces, via a space, at least a part of an outer edge of the movable member accommodated in the accommodation space and regulates displacement in an in-plane direction of the main surface.
Data Source
AI summary
A MEMS device includes: a base (substrate) having a support part and a fixed electrode (detection electrode); a movable member supported on the support part with a main surface facing the fixed electrode; and a lid joined to the base and forming an accommodation space in which the movable member is accommodated. The lid has an abutting part which faces, via a space, at least a part of an outer edge of the movable member accommodated in the accommodation space and regulates displacement in an in-plane direction of the main surface.