Investigation on curing characterization of epoxy molding compounds with different latent catalysts by thermal, electrical and mechanical analysis

Highlights: • Various analytical methods were applied to observe EMC curing characteristics. • These curing characteristics depend on the latency of catalysts. • The correlation between thermal, electrical and mechanical characteristics was identified. -- Abstract: This research was conducted to investigate comprehensively curing characteristics of epoxy molding compound (EMC) with various latent catalysts by using their thermal, electrical and mechanical properties. The conversion prediction on isothermal condition for three types of organophosphine based catalysts was studied by model free method with differential scanning calorimetry (DSC). The T₂ relaxation time was measured by time-domain nuclear magnetic resonance spectroscopy (TD-NMR) in order to compare the cross-linking density for each catalyst according to curing time. The results of DSC and TD-NMR showed that catalysts with lower latency reached curing in a shorter time. Furthermore, we observed the electrical-mechanical characteristics of EMC using additional thermal analysis. The ion viscosity was measured by dielectric analysis (DEA) according to the curing time, and the results suggested that the ion viscosity and the volume resistivity were lower for the catalyst with a slower curing rate. Dynamic mechanical analysis (DMA) was performed to compare activation energy of glass transition and glass modulus of final product. It was shown that the use of a catalyst with a low latency increases the modulus against external physical forces. In conclusion, our results demonstrated that the various analytical approaches are highly significant to understand the curing characteristics of EMC, which helps select appropriate catalysts in order to enhance the reliability of EMC.