Bonding Effect of Metal Thermal Interface Material on Oversized Flip Chip Package

Efficient heat dissipation is a major challenge for large flip-chip package with high power consumption. Due to its high thermal conductivity, metal lid is commonly found as a thermal interface material (TIM) between the die and the environment. In this work, a method for evaluating performances of ultrathick metal TIM is proposed. It is based on Non-destructive scanning acoustic tomography (SAT) with two interface waves for the constant-depth scan (C-scan) and a transmission scan (T-scan). In addition, the deterioration of the TIM bonding during reliability tests was also analyzed. Finally, a scheme to enhance the TIM bonding performances is proposed.

I. INTRODUCTION

With the rapid development of wafer processing, Moore's law has started to approach its limit. The demand for high-density, high-power, and super-large packaged devices has increased to meet the rapid growth of the energy required to process electronic devices [1]. Therefore, the heating problem of oversized packaged devices should be urgently solved. As devices work at high temperature for a long time, their reliability is affected because their lifetime may be considerably reduced with increased operating temperature [2].