Effect of Shear Speed on the Ball Shear Strength of Sn-3Ag-0.5Cu Solder Ball Joints

Abstract

The effect of shear speed on the ball shear strength of Sn–3wt%Ag–0.5wt%Cu solder ball joints has been investigated. The effect of electrode type on shear strength under various aging conditions was also studied. A linear relationship was obtained between the logarithm of shear speed and the ball shear load in the joints with Cu electrodes, regardless of aging conditions. Fracture occurs in the solder at lower shear speeds (below 10–3 m/s) in joints both with Cu and with electroless Ni–P/Au plated electrodes. The fracture mode changes from a solder fracture to an intermetallic compounds (IMC) fracture at higher shear speeds (above 0.5 m/s), regardless of electrode type. This means a ductile-to-brittle transition exists in the shear speed range from 10–3 m/s to 0.5 m/s. In the case of the joint with the Ni–P/Au electrode, shear strength decreases at higher shear speeds (above 0.5 m/s) due to the ductile-to-brittle transition.