Aging treatment characteristics of shear strength in micro solder bump

Abstract

The shear strength of the Cr/Cr-Cu/Cu UBM structure in both the high-melting solder bump and low-melting solder bump after aging were evaluated. SEM and TEM were examined in the intermetallic compounds and bump joint profiles at the interface between solder and UBM. The shear load concentrated on the bump was analyzed by finite element method. In 900-hour aging experiments, the maximum shear strength of Sn-97 mass% Pb and Sn-37 mass% Pb decreased by 25% and 20%, respectively. The growth of Cu6Sn5 and Cu3Sn was ascertained by the aging treatment. The crack path changes from the interior of a solder to the intermetallic compound interface was evaluated. Compared with the Cu-Sn IMC, the amount of Ni-Sn IMC was small. The Ni layer is considered as the diffusion barrier.