A 3D transient heat transfer and cure kinetic coupled finite element model was developed to simulate the microwave curing process of underfill material in flip-chip packaging. Temperature distribution inside underfill was evaluated by solving the an-isotropic heat conduction equation including internal heat generation produced by exothermic chemical reactions. A non-isothermal cure kinetic method was used to validate the model. The cure kinetic parameters of the model were determined by differential scanning calorimeter (DSC) from the underfill precursor. Numerical results show that variable frequency microwave (VFM) oven can process underfill materials with uniform temperature distribution and conversion. (C) 2004 Elsevier B.V. All rights reserved.