Solder Ball Joint Reliability with Electroless Ni/Pd/Au Plating-Influence of Electroless Pd Deposition Reaction Process and Electroless Pd Film Thickness

ABSTRACT On the solder ball joint reliability, the influence of electroless Pd deposition reaction process and Pd film thickness in electroless Ni/Pd/Au plating was examined. It was found that the solder joint reliability was influenced by Pd replacement reaction time and was excellent when replacement reaction time was short. On the basis of the solder joint reliability obtained after multiple reflow cycles and thermal aging, the optimum thickness of the Pd film was found to be 0.05–0.2 μm. We inferred that the high adhesion at the dendrite layers of IMCs/solder interface resulted in excellent solder ball joint reliability after the reflow cycles. We consider that the thickness of the IMCs is one of the factors that influences the solder joint reliability after thermal aging. In (Cu, Ni, Pd)6Sn5 IMCs that contained trace amounts of Pd, the growth of the IMCs is prevented by Pd, resulting in excellent solder ball joint reliability after thermal aging.