Physical Mechanism of Interfacial Thermal Resistance in Electronic Packaging Based on a Mixed MD/FE Model

A multiscale model is constructed to study interfacial thermal resistance in electronic packaging. The model combines a molecular dynamics simulation for the critical regions within the system with a finite element (FE) method for a continuum description of the remainder of the system. For nonequilibrium simulations, the establishment of the proper boundary condition is very difficult. In this mixed model, the continuum subdomain serves primarily as a boundary model that provides the low frequency impedance and a sink for the energy associated with outgoing waves of the molecular dynamics model. The simulations results show that the temperature distribution is nonuniform along the interface. At primary stage, the interfacial thermal resistance is unstable and will become very large at certain time steps. At the last stage, the change of interfacial thermal resistance tends to be stable. There are few direct experimental measurements of the interfacial thermal resistance between dissimilar materials, while the similar experimental results support the conclusions in this paper.