Physics-of-failure analysis of cooling fans

The use of cooling fans is a low-cost solution for thermal management in electronic products. Cooling fans are used to create designed airflow to cool down the host system. Since many failures in the field can be traced back to thermally-related issues in electronic products, the reliability of cooling fans is a critical part of the overall reliability of thermal management systems in electronic products. When cooling fans fail to work at the designed operating point, the host system will undergo overheating, which will degrade its performance and lead to intermittent failures and catastrophic failures. There is growing interest in the prognostics and health management (PHM) of cooling fans in electronic products. This paper works on the implementation of failure modes, mechanisms and effects analysis (FMMEA) of cooling fans in electronic products, and discusses three situations in which cooling fans can fail to provide the designed airflow to cool down their host systems. An overview of the cooling fan bearing is provided, and bearing reliability issues are also reported. Finally, the prioritization of potential failure mechanisms was performed with the estimation of risk priority numbers based on past experience and engineering judgment.