Impact of Immersion Cooling on Thermo-Mechanical Properties of PCB's and Reliability of Electronic Packages

Abstract

Immersion cooling technique is used for the thermal management of high-density data centers to avoid overheating of components and failure of servers. However, to use this as a viable cooling technique, the effect of dielectric coolants on the reliability of server components needs to be evaluated. Previous work reported contradicting findings for Young’s modulus of PCBs, providing motivation for this work. This study focuses on effect of immersion cooling on the thermos-mechanical properties of printed circuit board (PCB) and its impact on reliability of electronic packages. Changes in thermo-mechanical properties like Young’s modulus (E), Glass transition temperature (Tg), Coefficient of thermal expansion (CTE) of PCB and its layers due to aging in dielectric coolant are studied. Two types of PCBs using different material namely 370HR and 185HR are studied. To characterize Young’s modulus, Tg and CTE, dynamic mechanical analyzer (DMA) and Thermo-mechanical Analyzer (TMA) is used. Major finding is Young’s modulus and CTE is decreasing for PCBs after immersion in dielectric coolant which is likely to increase reliability of electronics package.