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We developed superhydrophobic (SH) silica/epoxy nanocomposite coating as an encapsulant to improve device reliability. The SH surface was generated by spin-coating of a silica/epoxy nanocomposite, followed by an oxygen reactive ion etching that exposes silica nanostructures for high surface roughness, and a subsequent hydrophobic treatment for low surface energy. As a result, a water contact angle of 161.2° and a contact angle hysteresis of 1.7° were achieved under an optimized condition. Such SH coating showed good stability under humidity at elevated temperatures and was applied on the triple track resistor (TTR) test coupons. It is found that the self-cleaning encapsulant successfully improves the test device reliability, and the coated TTR showed less degradation of resistance and leakage current in the temperature humidity bias test. In addition, the effect of different types of epoxy resin on reliability improvement was studied.