Solder reflow prediction of hybrid pad packaging system

In this work, a methodology of solder reflow geometry prediction for hybrid-pad-shapes (HPS) system is developed. In the reflow process, many parameters will influence the final joint shapes and there is no accurate closed-form solution for non-axisymmetric type solder pad prediction such as elliptical and rectangular pads. However, conventional approach like energy-based simulation model for predicting geometries in multiple/hybrid joint arrays is very difficult and time consuming. This work presents an approach combining the analytical and the energy-based methods and is capable of solving any kind of HPS system, such as round, elliptical, and rectangular pads. Furthermore, a detailed geometry information of the solder joints can be transferred to any conventional pre-processor/solver such as MSC/PATRAN, MSC/NASTRAN, LS-DYNA3D, ABAQUS and ANSYS for reliability analyses. The objective of this work for predicting multiple/hybrid solder reflow geometries in ball grid array type interconnects is to achieve optimal joint geometries from the standpoint of improved yield and better reliability cycles under thermal loading. Furthermore, results presented in this study can be used as a reference for area array interconnects design.