SYNTHESIS OF NOVEL TRIFUNCTIONAL EPOXY-RESINS AND THEIR MODIFICATION WITH POLYDIMETHYLSILOXANE FOR ELECTRONIC APPLICATION

The modification of novel trifunctional epoxy resins with silicon rubb er to reduce stress while maintaining a high glass transition temperat ure is described. Trifunctional epoxy resins were synthesized from the condensation of 4-hydroxybenzaldehyde, chloroacetaldehyde or crotonal dehyde with phenol, followed by epoxidation with a halohydrin. The str ucture of the synthesized triphenols was characterized by infra-red, m ass, and nuclear magnetic resonance spectrometry. Toughening of trifun ctional epoxy resins was achieved by hydrosilation with side chain met hyl hydrogen siloxanes. The dynamic viscoelastic properties and morpho logies of neat silicon rubber-modified epoxy networks were investigate d. The mechanical properties of encapsulants formulated from the synth esized silicone rubber-modified epoxy resins were also studied. The di spersed silicon rubbers effectively reduced the internal stress of cur ed epoxy resins by reducing Young's modulus and the coefficient of the rmal expansion, while the glass transition temperature was slightly de pressed. (C) 1997 Elsevier Science Ltd.