Using Metallic Coatings to Enhance Thermal Contact Conductance of Electronic Packages

Recently a new thermomechanical model for coated contacts has been developed and shown to be quite accurate. After a brief overview of the theory, this paper concentrates on illustrating the utility of the new model by applying it to a common electronics packaging problem: heat transfer across an aluminum joint. Several soft metallic coatings are considered, and the thermomechanical model is used to predict the improvement in the contact conductance over that for a bare aluminum-to-aluminum joint. For each coating material, heat transfer performance is presented as a function of the coating thickness, the surface roughness, and the applied pressure. Finally, a parameter is proposed that allows candidate coating materials to be ranked.