Packaging induced die stresses - Effect of chip anisotropy and time-dependent behavior of a molding compound

This paper investigates the effect of the anisotropic behavior of the die and the time- and temperature-dependent behavior of epoxy molding compound on the packaging induced stresses for a quad flat package. Finite element (FE) simulations using isotropic and anisotropic properties of the die are carried out, respectively, and the results are compared. Creep experiments were performed at different temperatures ranging from -65degreesC to 230degreesC to obtain the long-term master curves and the related shift factors for the creep compliance of the molding compound. FE models which incorporate the viscoelastic constitutive relation of the material are constructed to simulate the thermo-mechanical stresses caused by the packaging processes. The influences of both the chip anisotropy and the viscoelastic behavior of the molding compound on the packaging induced stresses are discussed.