AMINOSILOXANE-MODIFIED EPOXY-RESINS AS MICROELECTRONIC ENCAPSULANTS

Amine-terminated poly(dimethylsiloxanes) (ATPDMS) were used to improve the toughness of a cresol-formaldehyde novolac epoxy resin cured with a phenolic novolac resin for electronic encapsulation application. Th e effect of molecular weight of amine-terminated polysiloxanes on the phase separation of the resultant elastomers from epoxy matrix were in vestigated. Mechanical and dynamic viscoelastic properties of siloxane -modified epoxy networks were also studied. The dispersed silicone rub bers effectively improve the toughness of cured epoxy resins by reduci ng the coefficient of thermal expansion and flexural modulus, while th e glass transition temperature was hardly depressed. Electronic device s encapsulated with the dispersed silicone rubber-modified epoxy moldi ng compounds have exhibited excellent resistance to the thermal shock cycling test and have resulted in an extended device use life.