Effect of organophosphine catalysts on the curing behavior of epoxy resins cured with a phenolic hardener

Abstract

In this study, we investigated the influence of reaction onset temperature on the formation mechanism of the cross-linked network structure of epoxy resins cured with a phenolic hardener, which is used as semiconductor encapsulants.Two types of organophosphine compounds were used as latent catalysts. The catalysts used were triphenylphosphine (TPP)and tetraphenylphosphonium tetra-p-tolylborate (TPPTTB), which react at different temperature. By evaluating changes in gel fraction and glass transition temperature (Tg) during the curing process, it was found that epoxy resin EP-TPPTTB reacted at high temperature using TPPTTB had a higher conversion at the gelation point compared to EP-TPP reacted at low temperature using TPP. Furthermore, it was found that the Tg of EP-TPPTTB was lower than that of EP-TPP during the process from gelation to full curing. This reflects differences in reactivity due to steric hindrance of the catalyst, suggesting that the catalyst influences the polymer chain growth mechanism and cross-linking mechanism.