Effect of Intermetallic Compound Bridging on the Cracking Resistance of Sn2.3Ag Microbumps with Different UBM Structures under Thermal Cycling

In this study, the effect of intermetallic compound (IMC) bridging on cracking resistance microbumps with two different under bump metallization (UBM) systems, Cu/solder/Cu and Cu/solder/Ni, a thermal cycling test (TCT) is investigated. The height Sn2.3Ag solders was ~10 µm, which resembles that most commonly used microbumps. We adjusted reflow time to control IMC level. samples levels were tested TCT (−55–125 °C). After 1000 2000 cycles (30 min/cycle), then polished characterized using scanning electron microscope (SEM). Before bridging, various cracks in both systems observed at IMC/solder interfaces after 1000-cycle tests. propagated as cyclic shapes from sides center became more severe cycle increased. With we could not observe any further failure all even when up 2000. discovered effectively suppressed crack formation TCTs.