Abstract: The thermal mechanical analyzer and micro-indentation test system were used to characterize the mechanical properties of isotropic conductive adhesive (ICA) with different silver contents. Based on numerical simulation, the thermal mismatch stress of cured ICA in flip chip packaging was analyzed. The results show that the glass transition temperature of cured ICA with high silver content is relatively higher and the thermal expansion coefficient is lower than those of cured ICA with low silver content. The elastic modulus and hardness of the cured ICA are higher in the glassy state than those in the high-elastic state, and the stiffness and strength are relatively larger for cured ICA with high silver content. On the whole, with the increasing temperature the maximum of thermal stress component increases, then declines rapidly, and decreases slowly, showing a "tadpole shaped" or "semi-tadpole shaped". In the glassy state, the conductive adhesive in flip chip packaging exhibits elasticity.