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This PhD project is a part of CreCon Industrial Consortium on Climatically Reliable Electronics. Overall aim of the PhD project is to investigate the change in failure mechanism especially formation of short circuit due to electrochemical migration/conductive anodic filament because of the change in scenario of application today. Change in application is connected to the widespread use, therefore get exposed not only to humidity, but also to various gases conditions such as sulphur and NOx gases. Gaseous conditions together with humidity changes local environmental conditions causing electrochemical failure modes due to different chemical species produced by the dissolution of gases in the water film. Another aspect is the use higher voltages and power, while miniaturizing the device. Both voltages and power changes the failure mechanisms. All these aspects are important to understand in order find mitigation measures.
Present Ph.D. project will focus on in depth investigation of failure mechanisms such as leak current, electrochemical migration, and anodic filament formation under synergistic environmental conditions such as humidity and gases and physical conditions such as high voltage and high power. Various types test PCB structures will be used for experiments. PhD project will specifically focus on:
• Effect of voltage and current: This part will focus on failure mechanism under varying voltage (including high voltage eg. upto 1000 Volts) with and without current limitation under humidity conditions producing varying water film thickness. Effect of process related contamination will be investigated.
• Effect of sulphur gases: Influence of sulphur gases such as H2S and SO2 in modifying the failure mechanisms under high voltage and humidity conditions will be investigated in detail using several test PCB structures depending on the requirement of the industrial partners.
• Effect of sulphur gases together with NOx gases: This part of the investigation will focus on synergistic effect of sulphur and NOx gases in defining failure mechanisms with and without humidity. Effect will be investigated under varying thickness of water film.
• Electrochemical modelling of the effect using Comsol Multiphysics: Simple electrochemical mdoels will be developed correlating the experimental data for leak current modelling under different conditions.
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