In this study, 60 solder compositions were examined in an effort to improve the integrity against impact loads of the solder joints on an electroless Ni–P/Au surface finish. The Ag, Cu, and Ni contents in the Sn-based solder varied from 0 to 4.5 wt%, 0 to 2.0 wt%, and 0 to 0.05 wt%, respectively. Impact shear tests were performed to investigate solder joint integrity after solder ball reflowing, after reflow soldering twice more, after storage at room temperature for 168 hours, and after storage at 150°C for 1,000 hours. According to the results, the Ag content should be as low as possible, the Cu content should be from 0.5 to 0.7 wt%, and the Ni content should be as high as possible. The Ag and Ni contents should be determined in consideration of the wettability and the board-level reliability of the solder joints.