Filler induced metal crush failure mechanism in plasticencapsulated devices

摘要

Filler particles from the mold compound can give rise to localstress on the integrated circuit die surface, cracking the passivation,resulting in a metal to polysilicon short or a metal to metal short. Themetal damage under the passivation is termed as metal crush. This studyshows that metal crush takes place only in plastic encapsulated devicesand is predominant in plastic packages with silicone gel die overcoat.Experiments and finite element simulations have shown that the use ofultra low stress molding compound without silicone gel die overcoateliminates metal crush failures. This study also presents the minimumsilicone gel die overcoat thickness that prevents metal crush failuresin plastic encapsulated devices with low stress molding compound andsilicone gel die overcoat