Abstract
Improved oil recovery in petroleum industry by development of intelligent oil and gas wells have been the main motivation for the work presented in this thesis. Intelligent wells require electronic systems that can operate in the demanding environment with high temperature (HT), high pressure (HP), vibration, shock and aggressive liquid. Maintainable and reliable miniaturized electronic systems together with longevity are highly important, as failures can be expensive and potentially dangerous. The purpose of this work has been to investigate behaviour and performance of components and materials for harsh environment applications involving high temperature (HT) and high pressure (HP). Passive components and interconnection technology have been investigated at temperatures ranging from 200ºC up to 250ºC and compared to performance when submerged in Silicone oil and pressurized at 1000 Bar at 200ºC. Short term characterisation of components and materials have been performed with respect to temperature and pressure and long term ageing test have been performed with respect to HT and HP conditions. A reliability and failure analysis of SnAg microbumps has been performed for a MEMS based 3D stack with respect to requirements in automotive industry. Al wire bonded to CuNiAu plating over Ag thick film have been found to display stable performance with respect to long term ageing and thermal cycling. The thin gold layer diffuses into the aluminium bond during the first hours of HT exposure, preventing further AuAl growth. The nickel provides lower interdiffusion, preventing formation of excess intermetallic during operational lifetime. Reliable operation for more than one year is feasible at 250ºC. Au thin film, thickness less than 1 µm serve as an acceptable alternative. No notable ageing effect independent of ambient pressure was observed for thin and thick film resistors at 200ºC. Ageing effect was accelerated at 250 ºC. Excellent characteristics with respect to temperatu
