Passive phase change tower heat sink & pumped coolant technologies for next generation CPU module thermal design

Increasing thermal demands of high-end server CPUs require increased performance of air-cooling systems to meet industry needs. Improving the air-cooled heat sink thermal performance is one of the critical areas for increasing the overall air-cooling limit. One of the challenging aspects for improving the heat sink performance is the effective utilization of relatively large air-cooled fin surface areas when heat is being transferred from a relatively small heat source (CPU) with high heat flux. Increased electrical performance for the computer industry has created thermal design challenges due to increased power dissipation from the CPU and due to spatial envelope limitations. Local hot spot heat fluxes within the CPU are exceeding 100 W/cm2, while the maximum junction temperature requirement is 105 C, or less.