Inertial Sensor Lid Mounting for Resonance and Thermal Stability
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Solution Overview
Problem
Inertial sensors, particularly MEMS sensors, are adversely affected by resonant mechanical modes, stress, and misalignment due to supporting structures that shift with temperature and aging, exacerbated by circuit boards made of composite materials that introduce additional error sources.
Innovation Solution
A sensor lid is mechanically coupled to a support structure within a sensor assembly, eliminating the need for a printed circuit board and creating a stiffer assembly that pushes mechanical modes to higher frequencies, thereby reducing sensor errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a sensor is mounted to a circuit board using soldering and screw/bolts, then the sensor can be securely attached, but multiple mechanical interfaces and resonant modes are introduced that negatively interact with the sensor
Solution Approach 1:
The patent removes the circuit board from the mechanical mounting path between the sensor and supporting structure. The sensor is directly mounted to the supporting structure, extracting the harmful intermediate circuit board that introduced multiple mechanical interfaces and resonant modes.
Solution Approach 2:
The mounting structure is segmented into distinct functional zones: the circuit board is separated from the mechanical mounting function, leaving only electrical connection purposes. The mechanical mounting is handled by a dedicated support structure with isolation elements.
2Ease of manufacture
If a circuit board made of composite materials is used to mount the sensor, then electrical connections can be established, but the composite materials are not mechanically stable and introduce extra error sources
Solution Approach 1:
The circuit board's functions are segmented: electrical connection is separated from mechanical support. The circuit board retains only its electrical function while mechanical support is provided by a dedicated structure made of mechanically stable materials.
Solution Approach 2:
A dedicated support structure acts as an intermediary between the sensor and the circuit board, providing mechanically stable support while allowing the circuit board to focus on electrical connections. Isolator structures mediate between the support structure and case to prevent stress transmission.
3Adaptability or versatility
If traditional mounting methods with multiple interfaces are used, then the sensor can be assembled with standard components, but the different resonant modes create negative interactions with the sensor
Solution Approach 1:
The harmful intermediate mounting interfaces are extracted from the system. The sensor is directly mounted to the supporting structure, eliminating the chain of interfaces that created resonant mode interactions and measurement errors.
4Temperature
If the supporting structure shifts over temperature and aging, then material expansion/contraction occurs naturally, but this causes misalignment and stress on the mounted sensor
Solution Approach 1:
Isolator structures are introduced as intermediaries between the supporting structure and the sensor/circuit board assembly. These isolators accommodate thermal expansion and aging shifts of the supporting structure while preventing stress and misalignment from being transmitted to the sensor.
Data Source
AI summary
A sensor assembly comprises a case structure, a support structure having a plurality of surfaces and located within the case structure, and at least one sensor package having a sensor lid. The sensor lid is mechanically coupled to one of the surfaces of the support structure. At least one sensor board is connected to the at least one sensor package. At least one isolator structure is coupled between at least one of the surfaces of the support structure and the case structure.