Characterization of Fatigue Performance for Bulk Epoxy Molding Compound in Sustained High Temperature Exposure Up to 1 Year Aging

Abstract The reliability of electronic devices is significantly influenced by the fatigue failure of packaging materials under prolonged high-temperature exposure. Epoxy molding compounds (EMCs) are widely used to encapsulate and protect semiconductor devices against contaminants, corrosion, and thermomechanical stresses. In automotive underhood environments, electronic packages experience sustained high temperatures, which can lead to EMC fracture, enabling moisture and contaminants to penetrate and accelerate failure. Despite the critical role of EMCs in electronic reliability, limited research exists on their fatigue resistance. This study investigates the fatigue performance of two developmental EMCs intended for automotive applications under prolonged exposure to 100 °C for up to 360 days. Fracture toughness and stress–life relationships are analyzed, and the effects of aging on inelastic work per cycle are evaluated. S–N curves are reported, demonstrating the applicability of the Basquin equation in modeling elastic fatigue behavior. By systematically examining the fatigue characteristics of EMCs, this study provides valuable insights for enhancing the reliability of electronic packaging materials in harsh automotive environments.