Linear fracture mechanics analysis on growth of interfacial delamination in LSI plastic packages under temperature cyclic loading-Part II: Material properties and package geometry factors

For Part I see ibid., vol.21, pp.422-27 (Nov. 1998). A comprehensive study is made to evaluate the effects of material properties and package geometry factors on the delamination growth along the interfaces of a die-bonding layer and the bottom surface of the die pad in large scale integration (LSI) packages subjected to temperature cyclic loading. The effects of the coefficient of thermal expansion and Young's modulus of both the encapsulant resin and die-bonding material, as well as such package geometry factors as thickness, width, and chip size, are investigated. Numerical fracture mechanics analyses are conducted for three models of delamination geometries, for which relatively high stress intensity factors are induced. The effects of these design parameters on delamination growth are determined, and guidelines for designing packages with leadframes made of Cu alloy or Fe-42%Ni alloy (alloy 42) are established.