Investigation on the Joule heat and thermal expansion in flip chip package by electro-thermo-mechanical coupling analysis

Abstract

As the feature size of flip chip (FC) decreasing, the chip power increasing rapidly. Joule heat in the circuit will cause the temperature to rise and lead to thermal expansion in the FC package assembly. Therefore, the reliability of FC package under the electro-thermo-mechanical coupling interaction should be deeply investigated. In this paper, the electro-thermo-mechanical coupling analysis of the reliability of FC package was performed by finite element simulations. Taking into account the temperature dependence of the resistivity, the traces, pads, and solder bumps were analyzed using linearized resistivity. Firstly, the 3D finite element model of the FC package system was established. Then, the Joule heat and thermal expansion in flip chip were analyzed by thermal-electric-mechanic coupling method. Thus, the current density and temperature distribution were obtained, at the same time, the thermal stress and deformation were also analyzed. Moreover, the effects of current, operating temperature, and underfill material properties on Joule heat and thermal expansion in flip chip were deeply analyzed. This research work provides important guidance for the reliability design of flip chip.