The study of Thermosyphon solution for high performance switch

Abstract

Thermal is becoming more and more challenging for Data center switch in recent years along with increased switching bandwidth demand. For next generation 800G switching technology, TDP of 25.6T ASIC chipset called Tomahawk 4 (TH4)-112G from Broadcom is up to 580W, which is 60% power increase than TH3 of previous generation 12.8T. The required thermal performance for heat sink represented by R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ca</inf> should be within 0.043°C/W based on 105°C junction limit at 45°C ambient temperature, which farther beyond thermal performance that traditional heat sink can achieved refer to 0.09°C/W of thermal performance achieved with vapor chamber-based heat sink in 1U 400G belly-to-belly chassis.In this paper, thermosyphon solution as an alternative solution of traditional heat pipe or vapor chamber-based heat sink in air cooling space is studied to identify thermal feasibility for 25.6T ASIC chipset in 1U form factor chassis. Experiment result presents that thermal performance of thermosyphon prototype is 0.077°C/W under 312.8W power consumption in a 1U 400G switch. Furthermore, thermal correlation analysis between experiment and simulation result is conducted to calibrate thermal modeling of thermosyphon, which will be used for further study on thermosyphon solution as a viable candidate for high-power chipset cooling.