Prediction of Material Properties of Epoxy Materials using Molecular Dynamic Simulation

Epoxy is widely used in electronic packaging and its performance is very important to the reliability of electronic packages. It is necessary to understand the mechanical properties of epoxy materials at a fundamental level as a guide in the experimental design of epoxy resin for high reliability. Molecular modeling is widespread in its usage and has been used to investigate the mechanical properties of polymer at the molecular level, including the investigation of the Tg. The present study is focused on the material properties of the cured epoxy resin. MD model of the epoxy was built using the amorphous module. MD simulations were carried out starting at 225degC under a pressure of 0.1Mpa using the ensembles of the constant number of particles, constant-pressure and constant temperature (NPT). Temperature was lowered to room temperature at a rate of 10 degC/200ps. Each subsequent simulation was started from the final configuration obtained at the preceding temperature. Non-bond interactions cut-off distance of 1.5 nm with a smooth switching function was used in all simulations. The simulation in each case study was performed with an interval of 1 femto second (fs) in each MD simulation step. Density of the epoxy at each temperature was calculated from the average specific volume. Tg was estimated based on the discontinuity in the slope of the density-temperature plot. The volumetric thermal expansion coefficient was obtained from the relation of the variation of the volume and temperature. The corresponding linear thermal expansion coefficient of the epoxy can be calculated. Young´s modulus and Poisson´s ratio of the epoxy can also be obtained from MD simulations. The predicted values of these mechanical properties are close to the experimental values