Long-term Stability Evaluation of Thermal Interface Materials (TIMs)

Thermal interface materials (TIMs) play an important role in thermal management of high-performance microprocessors. Thermal resistance of TIM dominates in the overall thermal dissipation path. It is necessary to provide an effective and reliable thermal dissipation path to dissipate a large amount of heat generated by the IC in order to maintain a low operating junction temperature. The objective of this study is to evaluate the stability of TIM under various reliability test conditions, such as thermal cycling, high temperature storage and HAST. Six types of commercially available TIM were evaluated. The change in die shear strength and TIM thermal conductivity after the reliability tests were recorded. It was found that the overall performance of all TIMs maintain throughout the thermal cycling and high temperature storage test period. There was a significant decrease in die shear strength after HAST which may lead to increase in thermal resistance. The interface integrity of TIM was very sensitive to moisture.