Reducing thermal interface impedance using surface engineering

The ever-increasing demand for more functionality of electronic and optoelectronic components led to increased packaging and thermal power densities. Higher processing density can be reached by developing thermal management solutions. The current technology in electronic packaging is to attach the die to heat spreader, using materials known as Thermal Interface Materials (TIM), such as solder or silver sinter pastes. The advantage of these materials is their relatively high thermal conductivity; however, there are major problems such as voiding and degradation of TIMs over time [1]. Furthermore, the thermal resistance of the interface between TIM and surfaces is considered as a serious issue in electronics packaging. In this work, we present a new scheme to reduce thermal impedance using surface patterning. Heat transfer enhancement in this method is based on increasing heat transfer surface area per unit die are and replacing TIM with patterns made of high thermal conductive materials such as Copper. Effect of different parameters such as pattern height, diameter and pitch on heat transfer rate was investigated both experimentally and numerically. Thermal resistance was measured using conventional 1-dimensional heat transfer setup. Finally, our experimental results show that using this scheme will increase effective thermal conductivity by almost 5-fold.