Thermal solution study of 51.2T Near-packaged optics switch

The rapid development of cloud computing, artificial intelligence application in recent years is driving the increase in bandwidth of switch ASIC. Power consumption of current generation 25.6T ASIC from Broadcom is up to 580W, which has about 60 % increase than previous generation. While the estimated power of next generation 51.2T ASIC will be 800+W, which will bring more challenge on power and thermal. The new architecture solution of Near-packaged optics(NPO) that multiple optical engines(OE) are mounted near to Switch ASIC is emerging in industry, which could save significant total power consumption of switch than traditional architecture of ASIC and pluggable optics. In order to solve the increased thermal challenge of multiple OEs and switch ASIC, in this paper, integrated heat sink solution, separate heat sink solution and cold plate liquid cooling solution were proposed for cooling 16 3.2T OE modules with 56W each and 835W ASIC. Based on TA analysis, different TIMs will be compared in terms of thermal performance and loading force. Furthermore, thermal simulation analysis with Flotherm was conducted to compare thermal performance between different solutions given the boundary conditions to provide valuable design reference of 51.2T NPO switch product development. The result shows cold plate liquid cooling has better performance than air-cooling solution. Separate heatsink will help to improve the cooling of OE chips while the ASIC temperature will deteriorate.