High-Thermal-conductivity Dummy Die and Finned Lid for Enhanced Liquid Cooling of 2.5D ICs

2.5D ICs have evolved to become the standard package platform for the integration of ever-more high-power GPUs and high-bandwidth-memory stacks (HBMs), and a key enabler of the rapid performance advancement we are witnessing today for applications such as high-performance computing (HPC), data centers, and artificial intelligence (AI). Today, direct-to-chip liquid cooling involving an integrated heat spreader and a cold plate on the GPU backside has been successfully deployed to cool high-power GPUs with a chip power as high as 1200 W. Moving forward, it is highly desirable to extend the operating range of a 2.5D IC to be able to handle a GPU power beyond 1200 W/chip without exceeding a maximum operating temperature of 100 °C to maintain high performance. In this work, it was demonstrated that with the incorporation of a large high-thermal-conductivity (HTC) dummy die and a large finned Cu lid to enlarge the effective cooling area without causing mechanical integrity issues, the maximum allowable GPU power in a thermally enhanced 2.5D package structure can be increased to 1700 W, while keeping other conditions identical.