T. H. Chen, T. I. Shih, United Microelectronics Corporation, Hsinchu, Taiwan

Summary: Thermal fatigue crack of lead-free solder joint within flip-chip package was investigated in this study by using scanning acoustic microscope (SAM) and SEM. The distribution of substrate delamination were mapped with the SAM of high depth resolution and observed with X-section SEM to find the mechanism of crack growth during the thermal reliability test.