Performance evaluation of thermal interface material (TIM1) in FCBGA+HS package using Automatic Test Equipment (ATE) tester and package reliability tests

Thermal interface materials (TIM) are used in flip-chip BGA packages between the die and the heat spreaders (TIM1) and the heat spreader and the heat sink (TIM2), for a better thermal conduction path to the external heat sink solution. With an increase in demand for high die functionality and performance, the power density on the die is increasing, owing to use a better TIM1 to reduce the overall package thermal resistance, and in return, the thermal resistance from the package to the external heat sinks. Performance evaluation of TIM1 has to be done not only at the Beginning of Life (BOL) but also at the End of Life (EOL) by conducting various package reliability tests. This helps to determine the long-term stability of the material properties. This paper presents a process flow for the performance evaluation of TIM1 in FCBGA+HS packages. Two different TIM1 materials are selected for this study and test vehicle samples are assembled. These samples are then tested on Automatic Test Equipment (ATE) tester system for BOL thermal performance evaluation. After the BOL tests, the samples are sent for environmental reliability tests. At every read point during these reliability tests, the samples are again evaluated for thermal performance on the tester and visual non-destructive failure analysis technique CSAM is used to investigate the integrity of TIM1. This paper will present thermal performance data comparison from the BOL and EOL tests on an ATE tester, and the results of the reliability tests on device samples with different TIM1 materials.