Rate Dependent Interface Delamination in Plastic IC Packages

This paper examines the quasi-static steady-state crack growth at the interface joining viscoelastic polymeric material and hard substrates assisted by the internal vapor pressure in IC packages. Void growth and coalescence in the fracture process zone at the interface is modeled by a nonlinear viscous porous strip incorporating vapor pressure effect. The polymeric material surrounding the fracture process zone is taken as the nonlinear viscoelastic solids. To facilitate the understanding of vapor pressure, mode mixity and rate effects on the relationship between interface toughness and crack velocity, two computational models have been employed: (i) elastic background material with viscous fracture process zone (FPZ); (ii) viscoelastic background material with viscous fracture process zone. The present simulations offer some insights into viscoelastic delamination of polymer-substrate interfaces in plastic IC packages.