System-Level Flip-Chip Ball Grid Array Solder Joint Reliability Assessment Under Different Methodologies and Correlation with Accelerated Thermal Cycling Experimental Data

Abstract

Even if there are decades of research available in solder joint reliability (SJR), there is still a lack of enough constitutive solder models to adapt new materials on the market [1]. The high computing power available today lets us investigate the complex stress state in the solder joints due to underfilling or conformal coating [2], [3]. In the last couple of years, the research is transitioning from component and board-level analyses to system-level analyses. Densely populated product boards constrained in housings introduce additional stress in the solder joints. New prediction models and methodologies thus emerge [4], [5], [6]. The scope of this paper is to identify a methodology that can be both reliable and efficient for evaluating electronic components in their use environment. We consider lifetime prediction methodologies from the literature [7], [8], as well as Sherlock™ and the Creep Strain Energy Density Ratio (SED-R) approach based on the Coffin-Manson fatigue model. We predict the lifetime of two flip-chip ball grid array (FCBGA) packages under different system-level configurations and loading. We correlate theoretical results with accelerated thermal cycling test results. From the methods considered in this work, we consider SED-R to be the best approach for system-level solder joint reliability assessment because of its transparency and versatility. The availability of Weibull data on packages could be a game-changer in the system-level SJR analysis by increasing the precision of methodologies as SED-R and Sherlock™.