Application of Moire´ interferometry to determine strain fields and debonding of solder joints in BGA packages

Moire´ interferometry (MI) has proven to be a very useful tool for testing the reliability of many different electronic packages. Historically, MI has been used for monotonic thermo-mechanical loading or steady-state conditions induced strain measurements but never for fatigue testing. Interface failure of microelectronics devices is a significant concern in packaging since it may cause a device to malfunction while in service. In this study, solder joint fatigue mechanisms, and their interfaces, are experimentally observed by means of a MI system. In addition, scanning electronic microscopy (SEM) was extensively utilized to support and document the MI observations. The combination of these two techniques and the robustness of the MI system is shown to be effective for the determination of the failure mechanisms of electronic packaging interfaces.