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

A comprehensive study is made to evaluate the effects of material propertie s and package geometry factors on the delamination growth along the interfa ces of a die-bonding layer and the bottom surface of the die pad in large s cale integration (LSI) packages subjected to temperature cyclic loading. Th e effects of the coefficient of thermal expansion and Young's modulus of bo th the encapsulant resin and die-bonding material, as well as such package geometry factors as thickness, width, and chip size, are investigated. Nume rical fracture mechanics analyses are conducted for three models of delamin ation geometries, for which relatively high stress intensity factors are in duced. The effects of these design parameters on delamination growth are de termined, and guidelines for designing packages with leadframes made of Cu alloy or Fe-42%Ni alloy (alloy 42) are established.