Thermal characterization of multi-die BGA packages

Ball Grid Array (BGA) packaging offers a number of design and manufacturing advantages to integrate multiple devices in standard package formats. However, the increasing device pin counts, device speeds, and power dissipation introduce numerous routing, electrical, and thermal design challenges. This paper details an experimental and theoretical study on the design parameters that affect the thermal performance of 27 mm multi-die BGAs. Key parameters include: die size, die power, attach surface (a copper pad or soldermask), metallization under soldermask or lack there of, thermal vias, power planes and the effect of soldermask thickness. Using superposition of temperatures, the effect of background heating on the die due to other modules within the package, as well as the individual power dissipation of the die in question is determined. The result is a refined methodology to quickly evaluate viability of multiple die BGA packaging from a thermal performance point of view