Mechanical isolation of miniature resonant sensors and stress relieving packages
Mechanical isolation of miniature resonant sensors and stress relieving packages
A resonant sensor is a device that monitors the measured via the resonant frequency of a vibrating structure maintained at resonance. This thesis presents a detailed study of the design of the resonator and also stress relieving packaging techniques for microsensors in general. Both design studies were carried out using the ANSYS finite element analysis (FEA) package. After reviewing existing stress relieving packaging techniques, FEA was used to study common packaging materials and in particular the influence of the bond between sensor and support. This work identified the use of soft bonding materials and patterned bonds as a method of improving the degree of stress relief provided.
A key determinant of a resonant sensor's performance is the amount of energy coupled from the vibrating structure through its supports to the surrounding structure. Minimising this energy will improve the performance of the sensor by increasing the resolution of frequency and decreasing the influence of its environment upon the resonator. The FEA of resonator designs concentrated on Double Ended Tuning Fork (DETF) style resonators. The basic DETF resonator is attractive since it is a simple structure that vibrates laterally possessing easily predetermined resonances and a high degree of dynamic balance. FEA was used to simulate the resonator's natural frequency and stress sensitivity. The technique of assessing the degree of dynamic balance by observing the levels of stress generated at the resonator's supports was applied for the first time. Analysing the stress levels led to the inclusion of a supporting stub which reduced the stress by a factor of 75. The optimisation routine available within ANSYS was applied to this application further reducing the stress by up to a factor of 270.
University of Southampton
1997
Beeby, Stephen Paul
(1997)
Mechanical isolation of miniature resonant sensors and stress relieving packages.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A resonant sensor is a device that monitors the measured via the resonant frequency of a vibrating structure maintained at resonance. This thesis presents a detailed study of the design of the resonator and also stress relieving packaging techniques for microsensors in general. Both design studies were carried out using the ANSYS finite element analysis (FEA) package. After reviewing existing stress relieving packaging techniques, FEA was used to study common packaging materials and in particular the influence of the bond between sensor and support. This work identified the use of soft bonding materials and patterned bonds as a method of improving the degree of stress relief provided.
A key determinant of a resonant sensor's performance is the amount of energy coupled from the vibrating structure through its supports to the surrounding structure. Minimising this energy will improve the performance of the sensor by increasing the resolution of frequency and decreasing the influence of its environment upon the resonator. The FEA of resonator designs concentrated on Double Ended Tuning Fork (DETF) style resonators. The basic DETF resonator is attractive since it is a simple structure that vibrates laterally possessing easily predetermined resonances and a high degree of dynamic balance. FEA was used to simulate the resonator's natural frequency and stress sensitivity. The technique of assessing the degree of dynamic balance by observing the levels of stress generated at the resonator's supports was applied for the first time. Analysing the stress levels led to the inclusion of a supporting stub which reduced the stress by a factor of 75. The optimisation routine available within ANSYS was applied to this application further reducing the stress by up to a factor of 270.
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Published date: 1997
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Local EPrints ID: 463145
URI: http://eprints.soton.ac.uk/id/eprint/463145
PURE UUID: a5210418-021e-4572-a33b-2cc86544a05a
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Date deposited: 04 Jul 2022 20:46
Last modified: 04 Jul 2022 20:46
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Author:
Stephen Paul Beeby
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