Thermal contact conductance of typical interfaces in electronic packages under low contact pressures

This paper summarises the current models that are deemed appropriate for prediction of thermal contact conductances at the different interfaces commonly encountered between materials used internally in electronic packages. It further explores interfaces at the external package surface, such as between mold compounds and heat sinks. Tests are conducted for a mold compound, FP4450, held in contact with Al 6061 with various surface finishes, under lightly loaded conditions, in a vacuum environment. They are found to be adequately represented even by the early simple metal-to-metal models, such as Yovanovich (1982), and not significantly affected by minor flatness deviations. However, with a thin (10 μm) anodised coating on the aluminium surface, correlations that are derived primarily for metal-coating-metal surfaces would seriously overpredict the mold compound-anodised Al contact conductance. In general, the anodising process degrades the contact conductance due to an increase in roughness and hardness