Interfacial Reaction and Bump Shear Property of Electroplated Sn-37Pb Solder Bump with Ni Under Bump Metallization during Multiple Reflows

摘要

The interfacial reactions and bump shear properties of the electroplated Sn-37Pb (in wt.%) solder bumps with the Ni under bump metallization (UBM) were investigated as a function of the number of reflows. A continuous facetted Ni_3Sn_4 intermetallic compound (IMC) layer was formed at the interface between the solder bump and the Ni UBM during reflow. The thickness of the Ni_3Sn_4 IMC layer was 0.41 μm after 1 reflow, and then the thickness of the IMC layer increased with increasing the number of reflows. The shear properties of the bumps indicated the maximum values after 1 reflow, and then decreased with increasing the number of reflows. The fracture surfaces of the bumps showed ductile failure characteristics after 1 reflow, and then the fraction of the brittle fracture, induced by the IMC formed at the interface, increased with increasing the number of reflows.