Impact of heatsink attach loading on FCBGA package thermal performance

Flip-Chip Ball Grid Array (FCBGA) packages are prevalent in wide range of electronics applications including gaming consoles, mobile gadgets, telecommunications etc. The microelectronics industry is actively shifting towards smaller node sizes (32 nm, 28 nm etc.) and integrating multiple functionalities onto the die. This in turn increases the die power levels and more importantly drastically increases the die heat-flux densities. External heatsinks are typically needed in order to support high thermal power dissipation. The focus of this paper is to understand and quantify the impact of heatsink tilt on board-level thermal performance. her This in turn impacts the overall thermal performance as higher TIM-II bond line thickness results in greater thermal resistance. For high power applications (>;50W) wherein the desired system thermal resistances are very low (θ_ja <; 1 C/W), controlling the TIM-II thermal resistance is critical to achieve an overall low system thermal resistance. Experimental measurements were performed using a high power FCBGA thermal test vehicle (TTV). The scope of this study includes performing thermal measurements to -level thermal understand the impact of the following on board performance: 1. Package type: Bare Die FCBGA, Molded FCBGA & Lidded FCBGA 2. Impact of uneven heat-sink loading A novel method for characterizing TIM-II thickness variation is presented in this work. Upon characterizing the TIM-II BLT thickness variation, experimental measurements were performed to quantify the impact on the board-level thermal performance. Finally, merit analysis of the various package types in achieving low overall package thermal resistance will be presented.