A criterion for predicting delamination in plastic IC packages

Proposes that the critical stress intensity factor in linear elastic fracture mechanics, K/sub IIC/, obtained in an adhesion test between the leadframe and the mold compound can be used as a criterion for predicting delamination. A finite element stress analysis of the adhesion test determines K/sub IIC/ corresponding to the measured maximum strength. Delamination between the leadframe chip pad and the mold compound occurs when the maximum stress intensity value, K/sub II/ obtained for the package exceeds the critical value K/sub IIC/, in the adhesion test. The validity of the proposed criterion was verified by experiments on different plastic SOJ packages molded with different grades of molding compound under different moisture conditions. These findings suggest that for any new IC package, an optimized package design together with a mold compound with the necessary properties that will not result in delamination can be defined at the outset of package development.<>