Thermal management of high power dissipation electronic packages: from air cooling to liquid cooling

Performance-driven electronic packaging demands for thermal solutions of high power dissipation such as enhanced air cooling or, alternatively, liquid cooling technologies. This paper reports the characterization of air-cooled vapor chamber heat sink (VCHS) and liquid cooled heat sinks (LCHS) for electronic packages with a targeted power dissipation of 140W. The test vehicle flip chip plastic BGA package (FC-PBGA) involves a thermal test chip with a footprint of 12mm×12mm mounted on a high density substrate of 40mm×40mm with 1296 I/Os. The VCHS for characterization consists of a copper vapor chamber attached to the base of an Aluminum heat sink. Five types of thermal interface materials were used in the characterization study. In liquid cooling testing, two Aluminum LCHSs with microchannel width around 0.2mm were designed, fabricated and assembled with the chip. De-ionized water was used as coolant. Thermal measurements were conducted and the system-level thermal analysis shows that, for the VCHS, the overall thermal resistances ranged from 0.72 to 0.61°C/W, and maximum power dissipations around 100W are achieved given allowable chip temperature rise of 60°C. For the liquid cooling characterization, both thermal resistances and pressure drops were obtained at different flowrates and the system thermal resistances ranged from 0.42 to 0.35°C/W at pressure drop less than 0.1 bar, indicating the achievable power dissipation of 140 to 170W. This study reveals that there exist performance limits for the air cooling techniques and liquid cooling technique is a feasible candidate for cooling next-generation high-performance electronic packages.