MEMS Isolator Radial Beams for Thermal and Vibration Isolation
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Solution Overview
Problem
Disc resonator gyroscopes face issues with temperature sensitivity, residual stress, and vibration sensitivity due to coefficient of thermal expansion mismatch and rigid attachment between the die and package, leading to instability and increased costs in production and operation, especially in space applications.
Innovation Solution
A single layer micromachined thermal and mechanical isolator is bonded between the MEMS die and package, featuring radial isolation beams to absorb stress and distortion, and a vacuum package with electrical feedthroughs to reduce thermal and mechanical interference, allowing for improved thermal isolation and vibration attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the MEMS die is rigidly attached to the package, then mechanical stability is improved, but temperature sensitivity and vibration transmission increase
Solution Approach 1:
A micromachined isolator structure is introduced as an intermediary component between the MEMS die and the package. This isolator includes a central region that bonds to the die and radial isolation beams that extend to the package, acting as a mediator that provides mechanical support while isolating thermal and vibrational disturbances.
Solution Approach 2:
The isolator employs thin film structures with controlled mechanical properties, including flexible radial isolation beams that can deform to absorb vibrations while maintaining structural integrity. The thin film nature allows for both flexibility and strength, reducing vibration transmission while preserving mechanical stability.
2Stability of the object's composition
If the MEMS die is rigidly attached to the package, then mechanical stability is improved, but vibration transmission to the die increases
Solution Approach 1:
The radial isolation beams serve as intermediary elements that decouple the vibrational pathways between the package and the MEMS die. These beams provide a compliant connection that filters out high-frequency vibrations while maintaining low-frequency mechanical support.
Solution Approach 2:
The isolator structure changes the mechanical parameters of the connection, transitioning from a rigid connection with high vibration transmission to a compliant connection with vibration attenuation. The beam geometry and material properties are optimized to achieve desired vibration isolation characteristics.
3Ease of manufacture
If coefficient of thermal expansion mismatch exists between die and package, then manufacturing is simplified, but temperature sensitivity and residual stress increase
Solution Approach 1:
The isolator acts as a thermal buffer between the die and package, mediating the thermal expansion mismatch. The radial beams provide a compliant connection that accommodates differential thermal expansion while minimizing stress transmission to the sensitive MEMS structures.
Solution Approach 2:
The isolator structure is designed to accommodate thermal expansion differences between the die and package materials. The flexible beam structure allows for thermal cycling without generating excessive residual stress, maintaining reliability across temperature ranges.
4Object-affected harmful factors
If a micromachined isolator is introduced between die and package, then temperature sensitivity and vibration transmission are reduced, but device complexity increases
Solution Approach 1:
The isolator is segmented into a central region and multiple radial isolation beams, allowing for modular fabrication and assembly. This segmentation enables the complex function to be achieved through simpler, repetitive structural elements that can be manufactured using standard micromachining processes.
Solution Approach 2:
The complexity is managed by optimizing geometric parameters of the isolator structure, such as beam width, length, and thickness, to achieve the desired isolation performance. By carefully selecting these parameters, effective vibration and thermal isolation is obtained without requiring overly complex 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
The solution reduces temperature sensitivity and vibration transmission to the MEMS die, enhancing the stability and performance of disc resonator gyroscopes while maintaining compatibility with existing manufacturing processes and reducing production costs.
Implementation Method 1
coefficient of thermal expansion mismatch and rigid attachment between the die and package
Implementation Method 2
A single layer micromachined thermal and mechanical isolator is bonded between the MEMS die and package
Implementation Method 3
Long thin isolation beams can be used to provide thermal isolation against external temperature changes
Implementation Method 4
Weak and flexible beams can be used to tolerate large displacements with very little resistance
Implementation Method 5
featuring radial isolation beams to absorb stress and distortion
Data Source
AI summary
A single layer micromachined thermal and mechanical isolator may be bonded between a microelectromechanical system (MEMS) die and package. Small bond pads of the isolator are attached to the periphery of the die. The isolator material may be chosen to match that of the die, reducing CTE mismatch. Long thin isolation beams can be used to provide thermal isolation against external temperature changes, which may be conducted through the package. Weak and flexible beams can be used to tolerate large displacements with very little resistance. Thus, excessive stress or distortion to the package, from either CTE mismatch or external stress, may be absorbed by the isolator and will not be transmitted to the MEMS die. Beam rigidity may be designed to attenuate vibration of particular frequency range. The isolator can be readily inserted into an existing disc resonator gyroscope package in one thermal compression bond step.