SUMMARY

Out-of-plane displacement (warpage) is one of the major thermomechanical reliability concerns for board-level electronic packaging. Printed wiring board (PWB) and component warpage results from coefficient of thermal expansion (CTE) mismatch among the materials that make up the PWB assembly (PWBA). Warpage occurring during reflow processes and normal operations may cause serious reliability problems, such as severe solder bump failure, die cracking, and delamination of the solder bumps between electronic components and the PWB. In this research, a convective reflow and projection moiré warpage measurement system was designed and implemented. The developed system is the first real-time, non-contact, and full-field measurement system capable of measuring PWB/PWBA/chip package warpage with the projection moiré technique during any thermal reflow process. Automatic package detection and segmentation algorithms were developed for the projection moiré system. The algorithms are used for automatic segmentation of the PWB and assembled packages so that the warpage of the PWB and chip packages can be determined individually. Finite element modeling (FEM) and the projection moiré technique were used to study the effect of PWB warpage on the fatigue reliability of solder bumps on board assemblies. The experimental measurement and FE simulation results lead to a better understanding of the correlation between PWB warpage and solder bump reliability on board assemblies.