Leading indicators-of-failure for prognosis of electronic and MEMS packaging

The current state of the art in managing system reliability is geared towards the development of life-prediction models for un-aged pristine materials under known loading conditions based on relationships such as the Paris\´s Power Law [Paris, et al. 1960 1961], Coffin-Manson Relationship [Coffin 1954; Tavernelli, et al. 1959; Smith, et al. 1964; Manson, et al. 1964] and the S-N Diagram. There is need for methods and processes which will allow interrogation of complex systems and sub-systems to determine the remaining useful life prior to repair or replacement. This capability of determination of material or system state is called "prognosis". In this paper, a methodology for prognosis-of-electronics has been demonstrated with data of leading indicators of failure for accurate assessment of product damage significantly prior to appearance of any macro-indicators of damage. Proxies for leading indicators of failure have been developed including -micro-structural evolution characterized by average phase size and interfacial stresses at interface of silicon structures. Structures examined include electronics package, MEMS Packages and interconnections on a metal backed printed circuit board typical of electronics deployed in harsh environments. Since, an aged material knows its state the research presented in this paper focuses on enhancing the understanding of material damage to facilitate proper interrogation of material state. Mathematical relationship has been developed between phase growth rate and time-to-1-percent failure to enable the computation of damage manifested and a forward estimate of residual life.