Prognostics and health management of electronic packaging

The current state of the art in managing system reliability is geared toward the development of predictive models for unaged pristine materials. The current state of art allows the prediction of time-to-failure for a pristine material under known loading conditions based on relationships such as the Paris' power law [161, [17], the Coffin-Manson relationship [2], [13], [23], [24], and the S-N diagram. There is a need for methods and processes which will allow interrogation of material state in complex systems and subsystems 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 prognostication of electronics has been demonstrated with data of leading indicators of failure for accurate assessment of product damage prior to appearance of any macro indicators of damage. Proxies for leading indicators of failure have been identified. Examples of proxies include microstructural evolution characterized by average phase size and correlated to time and equivalent creep strain rate, and stresses at interface of silicon structures. Structures examined include an electronics package and microelectromechanical systems package and interconnections. The test vehicle includes packages that have been mounted on a metal-backed printed circuit board typical of electronics deployed in harsh environments. In application environment, the metal backing provides thermal dissipation, mechanical stability, and interconnections reliability. 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. A 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.