(Georgia Institute of Technology, 2019-07-26)
Li, Jiaxiong
The power electronics industry has been actively seeking encapsulant materials that can serve in harsher environments. For example, with the power semiconductors leading into SiC era, the higher operation temperature (250 ºC) have proposed great challenges on the packaging materials especially on epoxy molding compound (EMC) technologies, since the temperature exceeds the stability limit of typical epoxy (EP) chemistry. In this thesis, EP/triazine system was selected to develop high temperature stable resin system that can meet the temperature requirement of next generation power electronics packaging. In the first part of the thesis, different approaches were discussed to enhance the high temperature performance of a previously studied cyanate ester (CE)/ biphenyl EP blend which is impaired by the hydrolysis degradation of remaining cyanate groups. Firstly, the effects of different metal catalyst on the CE properties were discussed. Secondly, a triazine containing molecule triglycidyl isocyanurate (TGIC) was employed to increase the triazine content without increasing CE feed ratio to circumstance problem of unreacted cyanate groups. Finally, the high heat resistant novolac type CE was employed to form the NCE/EP blend, and their blends with different feed ratio were systematically evaluated. In the second part, a detailed characterization of a high heat resistant CE/novolac type EP blends and the investigation on their degradation under long-term high temperature storage were summarized. The effects of the CE concentration on the thermomechanical properties of the copolymer were explored, where a tradeoff behavior between the triazine content and crosslink density was accounted for the property change. In addition, the distinguished thermal degradation mechanisms in copolymer with different compositions were identified and illustrated. The knowledge obtained in this work can serve as a reference in the future to formulate EP/triazine based resin system for high temperature applications.