Author: Choy, Siu-hong
Title: Piezoelectric pressure sensors for microelectronic packaging
Degree: M.Phil.
Year: 2003
Subject: Hong Kong Polytechnic University -- Dissertations.
Piezoelectric polymer biosensors.
Piezoelectric transducers.
Piezoelectric materials.
Microelectronic packaging.
Department: Department of Applied Physics
Pages: xx, 163, 27 leaves : ill. (some col.) ; 30 cm.
Language: English
Abstract: It is envisaged that new sensor technology is needed for the future generation of integrated circuit (IC) packaging equipment which will be even more demanding in terms of precision and performance. For achieving this goal, there is a need for force sensor with higher sensitivity. In this project, different kinds of piezoelectric materials, including lead zirconate titanate (PZT) and PZT/epoxy 1-3 composites, were used as the transduction element to produce force sensor with higher sensitivity for microelectronic packaging applications. Soft PZT piezoceramic rings ASM 83 were used as the transduction elements in the sensors. PZT (PKI 552) powder was used to fabricate ceramic fibres. PZT fibres and epoxy (Araldite LY5210/HY2954) were used as the active and passive phases in a 1-3 composite structure. Their materials properties were characterized. PZT fibres were developed by a powder-based extrusion method. With a very slow heating rate and by controlling the ambient atmosphere, dense and crack-free PZT ceramic fibres were obtained. The diameter was ~0.4 mm. The microstructure of the ceramic fibres was studied by scanning electron microcopy (SEM). Electrical properties of the ceramic fibres, such as the dielectric, piezoelectric and ferroelectric behaviour were also investigated. Most of the electrical properties were comparable to that of the bulk PZT ceramics. PZT fibre/epoxy 1-3 composite discs with a diameter of 6 mm were fabricated with volume fractions of PZT ranging from 0.1 to 0.6. The ferroelectric, piezoelectric and dielectric properties of the composites were studied. The modified parallel and series model was used to calculate the theoretical values and compared with the measured parameters of the 1-3 composites. Using the measured parameters of 1-3 composites and epoxy, the relative permittivity, elastic and piezoelectric properties of a single PZT fibre were found. In addition, PZT fibre/epoxy 1-3 composite rings were fabricated with volume fraction of PZT ranging from 0.35 to 0.5. Prototype force sensors were fabricated using PZT ASM 83 rings and PZT fibre/epoxy 1-3 composite rings (o = 0.5) and their characteristics were measured. An optimum pre-stressing torque of 8 kgf-cm torque was used. Prototype sensors were calibrated by the back-to-back method and the mass-loading methods. From the back-to-back method, the sensitivity of the ceramic and composite sensors in the frequency range of 0.5-6.4 kHz were found to be 169 pC/N and 144 pC/N, respectively. Alternatively, from the mass-loading method, the sensitivity of the ceramic and composite sensors in the frequency range of 0.2-1.9 kHz were found to be 158.6 pC/N and 144.4 pC/N, respectively. A prototype tactile sensor with four sensing zones was fabricated. The sensor used PZT fibre/epoxy 1-3 composites as the transduction elements. The tactile sensor was calibrated by both the back-to-back method and the mass-loading methods. From the back-to-back method, the sensitivity of the sensing zones were found to be quite similar. In the frequency range of 0.5-5 kHz, the sensitivity was 23.5 pC/N. Alternatively, from the mass-loading method, the sensitivity of the 4 zones on the tactile sensor was 19.14 pC/N in the frequency range of 0.5-2 kHz.
Rights: All rights reserved
Access: open access

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