Localized TIM characterization using deconstructive analysis

Characterizing the thermal performance of thermal interface materials (TIMs) continues to be a challenge for flip chip ball grid array (FCBGA) packages. Steady-state methods have been studied extensively but due to the difficulty in making accurate case temperature measurements have accuracy limitations. Transient measurement techniques offer an attractive alternative to steady state. However, the implementation of a property extraction analysis is more difficult to perform for thermal die with discrete heater cells as found in this study. An experimentally based deconstruction method is presented to predict the local thermal resistance of TIMs as a function time and position on the die over a short pulse ranging from 0.7ms to 100ms. The model is developed for a particular TIM but can be extended to other TIMs following the proposed calibration procedure.