Influence of interface materials on the thermal impedance of electronic packages

The thermal properties of different interface materials (grease, ceramic, silicone and mica) have been investigated using the thermal impedance Zth(jω) represented in a Nyquist plot. It will be shown that an interface material not only influences the thermal resistance Rth = Zth(0) but the entire shape of the thermal impedance Nyquist plot. From the wind tunnel experiments the specific contribution of the interface materials to the overall thermal resistance could be determined.