研究期間：10108~10207;Due to the environment concern, Pb-free solder has been wildly used in electronic packaging industry. Yet, the Kirkendall voids at the solder joint interface is a major reason to degrade the reliability of the solder joints. Futhermore, with the shrinkage of the solder joint size, the reaction compound would be the dominant part in the entire solder joint. As the compound forms intensively in the micro solder joint, Kirkendall voids likely form at the interface. Therefore, Kirkendall voids at the solder joint play a critical role for the reliability of the solder joints. Take 3D IC TSV packaging as an example, the electroplate Cu via should be joined by thin Sn-based solder layer. Large amount of Cu-Sn compound formed at the solder joint interface, which results the formation of Kirkendall voids. Thus, the reliability of the solder joint is no longer depends on the solder joint materials only but it might be dominated by the formation of Kirkendall voids. Besides, the microstructure (texture orientation) of the electroplate Cu TSV is very critical to the formation of Kirkendall voids. So far, the relation between Cu-Sn joint strength and the formation of Kirkendall voids has not been studied systematically. The purpose of this project is to investigate and model relationship between the Cu-Sn joint reliability and the Kirkendall voids. In this proposed three-years project, we will investigate the effect of Cu preferred-orientation ((111),(220),(200),(Random)) on Kirkendall voids formation at the Cu/Sn joint interface. Three major approaches in this research: (1) physical property of different preferred-orientation electroplated Cu. (2) under thermal aging and electromigration, the effect of the Cu preferred-orientation on Kirkendall voids formation at the Cu/Sn joint interface. (3) under thermal aging and electromigration, the relationship between Kirkendall voids coverage and the solder joint strength.
