Electronic Packaging Reflow Shape Prediction for the Solder Mask Defined Ball Grid Array

The increasing need to create high density and fine pitch electronic interconnections presents a number of challenges. The fatigue-induced solder joint failure of surface mounted electronic devices has become one of the most critical reliability issues in electronic packaging industry. Prediction of the shape of solder joint has drawn special attention in the development of electronic packaging for its practical engineering application. Many solder joint models have been developed based on energy minimization principle (Patra et al., 1995) or analytical method (Heinrich et al., 1993; Liedtke 1993). These methods are extensively utilized to the shape design of solder joint. However, it is important to find a suitable method in real application. In this study, an efficient numerical method used to predict the shapes of solder joint is investigated, and the results are compared with Surface Evolver program (Brakke, 1994). The changes of geometric shape with respect to different parameters of solder joint are also discussed in this paper. The influences of the geometric parameters, such as volumes of solder joint, package weight, contact angles, pads sizes, solder surface tension, and gravity forces to the shape of solder joint, are investigated. Results presented in this study can be used to determined the optimally balanced stand-off height of single ball module (SBM) or multiple ball module (MBM) solder joint models.