Effect of Thermal Interface Materials on Thermal Performance and Reliability of Large Size Flip Chips

With the development of AI and high-performance processor, chip power consumption and power density continue to increase, and the heat dissipation of electronic packages faces great challenges. Thermal interface materials (TIMs) are used between the chip and the heatsink to improve the interface contact by filling the gap and exhaust air. Therefore, it is important to improve the heat dissipation performance of package. In addition to the excellent thermal properties, TIMs are also required to have good reliability. Due to package warpage and other mechanical stresses, a TIM will experience a range of compressive and tensile loads during package assembly and end use conditions, which even cause delamination and cracking in TIMs.In this work, we created a typical flip chip ball grid array (FCBGA) simulation model with a package size of 52.5 × 52.5mm. ANSYS ICEPAK was used for thermal analysis to discuss the effects of thermal conductivity, bond line thickness (BLT), coverage and other parameters of TIMs on chip heat dissipation performance. Besides, a Die-TIM-Lid sandwich model was established to investigate the effect of porosity and void size on junction temperature and hotspot concentration. Finally, quarter FCBGA models based on finite element method were employed to analyse the stress of TIMs on large size package. The distance between the lower surface of lid and the upper surface of die was measured to obtain the BLT.