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US 5,686,541 AGranted
Modification of epoxy resins with urethane prepolymer for electronic encapsulation
AssigneeNational Science Council
InventorsChun-Shan Wang, Tsung-Han Ho
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Abstract
A modified epoxy resin is prepared by mixing an isocyanate terminated urethane prepolymer with an epoxy resin in reactive conditions. The modified epoxy resin has a low internal stress when it is cured due to the flexible backbone of the urethane prepolymer incorporated therein, and has a high glass transition temperature due to a rigid oxazolidone structure formed via the epoxy ring opening with the isocyanate groups, and thus is useful as an electronic encapsulant.
Claims5
An encapsulation composition for semiconductor devices comprising a modified epoxy resin having the following formula I:
- ##STR18## Wherein R is ##STR19## wherein R.sub.1 is --(CH.sub.2).sub.m --, m is an integer of 1-10;
- R.sub.2 is hydrogen or methyl;
- R.sub.3 is --(CH.sub.2).sub.q --, q is an integer of 4-12;
- n is an integer of 5-1,000, and p is an integer of 1-3;
- Ar is phenylene, tolylene, naphthylene, ##STR20## ##STR21## ##STR22## or a phenol-aldehyde novolac epoxy resin backbone having the following formula:
- ##STR23## wherein X and R.sub.2 are the same as defined above, g is an integer of 1-6, R.sub.4 and R.sub.5 independently are hydrogen or ##STR24## wherein R.sub.6 is hydrogen or methyl.
3 more elements
Dependencies are inferred from the claim text.