Fundamental study on moisture absorption in epoxy for electronic application

This paper presents a fundamental study of moisture absorption in epoxy materials. Solid state nuclear magnetic resonance (NMR) techniques (both ¹H NMR and ²H NMR) were used to study the binding states of water within two epoxy formulations along with the possible plasticizing effects of moisture affecting the mobility of polymer chains. Absorbed water reduces the glass transition temperature. However, the presence of moisture has no significant effect on the polymer chain mobility at temperatures below the reduced glass transition temperature. Water in an epoxy in its rubbery state above the glass transition has a much higher mobility than in a polymer in its glassy state. The mobility of water absorbed by a polymer in its rubbery state is similar to that of pure water