Multiscale simulation of thermal contact resistance in electronic packaging

A multiscale model of thermal contact resistance (TCR) between two rough surfaces is developed. The lattice Boltzmann (LB) method and the traditional finite difference (FD) method are coupled to calculate the heat transfer between two rough surfaces. The LB method and the FD method are, respectively, applied to two different regions with different meshes (fine meshes and macro meshes). A coupling region for transmitting the boundary information between these two regions is established to ensure the continuity of physical parameters. In the multiscale model, the profile heights of actual surfaces are measured to construct the rough surface models, which have a higher accuracy than Gaussian surface. The elastic-plastic mechanics is applied to calculate the deformations of rough surfaces under pressure. A series of comparisons between both the numerical and experiments results are carried out to verify the validity of the multiscale model. The results show that the TCR is synthetically affected by several factors, such as surface roughness, surface flatness, pressure, microhardness, and thermal conductivity. In those parameters, the surface roughness, flatness, and thermal conductivity of materials exert great influences on the TCR under low-pressure condition. When the pressure increases, the pressure and microhardness play dominant roles in TCR.