P. Kongsubto, S. Kongwudthiti, N. Santipruksawong, J. Tippayamontri, T. Promket, Y. Singsa, K. Kamthongsuk, Spansion (Thailand) Ltd., Nonthaburi, Thailand

Summary: Due to the typically low thickness of inter-metallic compound at solder joint so it is difficult to inspect its thickness and characteristic even using SEM. In this study, the sample preparation technique was developed to facilitate the observation of such inter-metallic compound. Polishing medium was investigated to find out the most suitable polishing medium for IMC inspection purpose in both SnPb and Pb-free solder ball. With this technique, microstructure of the inter-metallic layers between Tin and Copper could be easily visualized.