IMPACT OF THERMAL AGING ON THERMOMECHANICAL PROPERTIES OF OIL-IMMERSED PRINTED CIRCUIT BOARDS

摘要

Immersion cooling technique is used for the thermal management of high-power density data centers to avoid overheating of components like printed circuit board (PCB), electronic packages and failure of servers. However, to use this as a viable cooling technique, the effect of dielectric coolant 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 mechanical properties of PCB and its impact on reliability of electronic packages. Changes in thermo-mechanical properties like Young's modulus (E), Glass transition temperature (Tg), of PCB and its layers will be studied when immersed in dielectric fluid and as a thermal acceleration factor, thermally aged at constant 125 C for period of 720 hours (one month). Two types of PCBs using different material namely 370HR and 185HR are studied. To characterize Young's modulus and Tg dynamic mechanical analyzer (DMA) is used. Major finding is Young's modulus is decreasing for PCBs after thermal aging in dielectric coolant which is likely to increase reliability of electronics package.