Nonlinear Superelement for the Reliability Assessment of Visco-Plastic Solder Balls

The paper proposes a novel approach to the modeling of the thermo-mechanical behavior of ball grid array (BGA) packages on printed circuit boards in the metal housing of electronic control units, which is needed for optimizing the design for reliability. The new approach reduces the computational effort significantly without compromising the result accuracy. The method is based on a modular system of reduced-order models (ROMs). Specifically, the energy-conserving sampling and weighting method (ECSW) for capturing complex material behavior is discussed as a key enabler. After introducing the method for a single solder ball, it is extended to the representation of all solder balls of the BGA by the same ROM in order to enable its application for practical cases. The results obtained with this 'Combined ROM' are compared with those of regular FEA in terms of accuracy and computational effort.