Numerical Case Study of Stress and Plastic Strain Distributions in BGA Solder Balls by Comparison of a Novel Inorganic Encapsulation and Conventional Underfill Variants

This paper presents a numerical case study of different packaging materials to reduce solder joint fatigue in ball grid arrays (BGAs). We compare a novel cement-based inorganic encapsulation with conventional polymer based underfill and edge bond variants, to study possible approaches to increase the lifespan of BGAs. Numerical finite element simulations (FEM) serve as an accompaniment for current experimental studies, in order to improve thermos-mechanical reliability of ball grid arrays (BGA). Therefore, two different possible design approaches for the inorganic encapsulation were compared with epoxy underfill and epoxy edge bond variants. The solder joint materials, Sn-3.0Ag-0.5Cu, Sn-3.5Ag and Sn58 Bi were simulated with a bilinear plastic material model. Furthermore, individual configurations were investigated under thermal cycling, to determine long-term behavior. The results of this case study can provide useful guidance for future applications of inorganic encapsulations and provide starting points for possible more detailed numerical and experimental investigations.