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Title: Performance of wire bonded interconnects under combined thermal and vibration loads
Author: Mirgkizoudi, Maria
ISNI:       0000 0004 7971 0530
Awarding Body: Loughborough University
Current Institution: Loughborough University
Date of Award: 2015
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Wire bonding is the process of providing electrical interconnections between an integrated circuit and the rest of the electronic package. Although wire bonding has been extensively utilised for chip-level interconnections, there is a lack of fundamental knowledge related to the reliability performance of wire bonded electronic devices in harsh environment applications such in aerospace and oil & gas industries. This thesis addresses the fundamental reliability aspects of Au and Pd-coated Cu wire interconnects bonded on Au and Al metallized bond pads respectively. The research described in this thesis investigates the performance of wire bonded electronic devices under complex harsh conditions. The mechanisms of the Au-Au and Pd/Cu–Al metallurgical wire bonded systems were elaborated by examining the mechanical, electrical and interfacial characteristics resulting from combined testing under high temperature and vibration conditions. Particularly, sine frequency vibration testing has been performed with the frequency ranging from 5Hz to 2000Hz and accelerations up to 20Grms combined with thermal loading up to 250°C. The performance of the two systems has been evaluated through ball shear and wire pull strength tests, electrical resistance measurements, wire integrity assessment and interfacial analysis. The results have shown that deterioration of the mechanical and electrical properties due to thermal fatigue is accelerated by vibration induced effects. The degree and manner at which each system is affected differs between the two metallurgical systems due to the different mechanical properties. In addition, a strong relation between the wire deformation and orientation of the devices on the vibration system has been found. It has been shown that the Au-Au system is more susceptible to wire deformation than the Pd/Cu-Al system due to the difference in hardness between the two materials. The electrical properties of the two systems showed a different change tendency that is time and temperature dependant. The AuAu system has been proven to be a better solution in terms of microstructural stability while the Pd/Cu-Al system presented interfacial defects such as cracks and voids.
Supervisor: Not available Sponsor: IeMRC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Mechanical Engineering not elsewhere classified ; Wire bonding ; Reliability testing ; High temperature ; Vibration ; Mechanical strength ; Electrical performance ; Interfacial characteristics