An investigation into fan reliability

Common failures in the electronic products can be traced back to thermal-related issues. While the power of electronic components and power densities are rapidly increasing, thermal management of electronic products becomes a challenge. Since the lifespan of electronic components is shortened drastically due to the high temperature, fans are widely used to create airflow in electronic products for cooling purpose. Therefore, fan is a critical part for thermal management in electronic products, and reliability of electronic products is heavily dependent on the fan´s reliability. There is a standard IPC-9591 that standardized fan´s performance parameters (including reliability). However, it is still difficult to compare the fan reliability directly among different fan manufacturers because they report their fans´ reliability using different parameter values in Weibull distribution, acceleration factors, and reliability tests. This paper reviews, compares, and discusses the approach of fan life expectancy calculation. It concludes that IPC-9591 recommends the most conservative values (biggest Weibull shape parameter, lowest test temperature, smallest acceleration factor) for reliability analysis. Since bearing is the most critical component in fan, its life is also discussed in the paper. Considering the very light bearing loads in fan, it is recommended that bearing life should refer to its grease life, not the fatigue life.