Solder fatigue is a recurrent concern for electronics system designers, particularly for ball grid array (BGA) components. The high pin count in a BGA makes it a common choice for cutting edge microprocessor, memory, and high-speed applications. However, the large package size, lack of compliant leads, and complex internal structure that allow for the high pin count can also make BGAs prone to solder fatigue failure during thermal cycling – a failure caused when the CTE mismatch between the package and its circuit board stresses the solder balls during cycling. Increasingly complex BGA packages are being used in novel product systems for enabling applications like autonomous vehicles, IoT, and electrification. Simulation has long been used to help predict BGA solder fatigue behavior; however, due to scaling issues, finite element methods are typically done only at the component-level and do not account for system-level effects. This is no longer an adequate approach to solder fatigue analysis as BGAs are being used in more integrated product systems that demand high reliability. Factors like housing over-constraint effects, component heatsink mounting, and board copper balance can create board flexure and combined loads that influence solder fatigue behavior. Preserving the geometry and mesh detail of individual solder balls while solving for system effects demands a multiscale approach. The mesh fidelity needed to accurately capture viscoplastic creep strains in the solder joints for solder fatigue prediction would create extremely inefficient system-level models. An automated submodeling approach is used to solve this multiscale simulation. This presentation outlines a multiscale submodeling methodology that can be used whenever system-level effects are necessary to accurately understand solder fatigue behavior of a BGA. Furthermore, it can be optimized to investigate multiple BGAs on an individual PCBA or multiple solder balls on an individual BGA in a single workflow.