Life margin assessment with Physics of Failure Tools application to BGA packages

Designers of electronic equipment are faced with the contractual obligation of guaranteeing that their products will fulfil the specifications on life duration. Classically, empirical methods based on databases and handbooks are used and features such as Mean Time Between Failure (MTBF) are provided. This paper presents how to use Physics of Failure (PoF) tools and results in order to provide the customer with a reliability feature, called life margin, based on Cycles To Failure (CTF) figures. The method defines and computes a life margin for 99% of the population in the given environmental life conditions. This feature is used to evaluate the different technological possibilities and decide the best trade-off to satisfy the customer’s requirement on life duration. The method has been applied to a given board and a given application, where the component, which limits reliability, has been identified as being packaged in a Ball Grid Array (BGA) package.