The effect of temperature on the mechanisms of Cu nanoparticle sintering: A molecular dynamic study

Abstract

Surface diffusion is considered the primary mechanism for low temperature sintering properties of Cu nano-solders. However, how surface diffusion affects the sintering quality and couples with the structure evolution mechanism is still unclear. We conduct an amount of randomized molecular dynamics simulations and reveal a temperature-dependent nanoparticle sintering mechanism. The results exclude the influence of non-major factors such as different sizes and contact angles. The atomic fast dynamic motions appear mainly at the sintering neck at 600 K and induce structure evolutions. It contributes to an abnormal mechanical performance increase, which could be further enhanced by pressure. Further investigations show that the phenomenological evaluations could hardly predict the sintering quality, as the internal structure strongly influences the tension strength. This comprehensive investigation provides a clear view of the coupled influence of temperature and pressure from the perspective of atomic motions, showing insights into the behavior of nanoparticles during the sintering process.