This collaborative GOALI project seeks to improve the fatigue life of thermosetting polymers through the addition of self-healing functionality. Thermosetting polymers are used in a wide variety of applications ranging from composite structures to adhesive joints to microelectronic packaging. Because these polymers have low strain-to-failure, they are highly susceptible to damage in the form of cracking. Fatigue loading is particularly problematic, causing small cracks to initiate deep within the structure where detection is difficult and repair is virtually impossible. These cracks often lead to catastrophic failure of the material. Self-healing functionality is accomplished by incorporating a microencapsulated healing agent and a catalytic chemical trigger within a polymer matrix. Fundamental research will be undertaken to address critical issues relevant to self-healing of fatigue damage. The ability to autonomically heal fatigue cracks in brittle polymers has the potential to lead to safer, more reliable materials in microelectronics and related applications and represents the first step in developing materials systems that possess greatly extended lifetimes. This GOALI project will enable collaborative efforts to explore this new technology for microelectronic applications. Results will lead to fundamental scientific foundations on which new design and production practices are based for improved fatigue performance. The proposed work will result in the education and training for two graduate students and one undergraduate research assistant. Moreover, several concepts from this project will be incorporated into a new senior undergraduate/ first year graduate level course entitled Autonomic Materials Systems.