Physics-of-failure approach for fan PHM in electronics applications

Fans have been a widely accepted solution for thermal management of electronic equipment. A fan is a critical component that affects the performance of expensive systems such as telecom equipment, power supplies, and server computers. The failure of a fan can lead to intermittent or catastrophic failures of target systems. There is a growing interest in prognostics and health management (PHM) of fans in the electronics industry. A physics-of-failure (PoF) based PHM approach enables the assessment and prediction of reliability under actual loading conditions. The PoF approach for fan PHM is based on a failure modes, mechanisms and effects analysis (FMMEA). FMMEA of brushless direct current (BLDC) fans was conducted while taking into consideration the expected application load conditions. The causalities between the failure causes and failure modes of BLDC fans were demonstrated by focusing on each failure mechanism. The prioritization of potential failure mechanisms was performed with the estimation of risk priority numbers. The life expectancies of fan ball bearings based on two potential failure mechanisms, including fatigue and lubricant deterioration, were calculated and compared to each other. The advantages and disadvantages of the PoF-based approach to PHM of fans are discussed. A potential application of the PoF based PHM approach to improve fan reliability assessment is addressed. Challenges for the PoF approach for fan PHM in the electronics industry are also addressed, including predicting overstress failures and reestimating reliability after design upgrades.