Effects of Electroplating Additives on the Interfacial Reactions between Sn and Cu Electroplated Layers

Three combinations of additives based on polyethylene glycol (PEG), Cl− ions, bis(3-sulfopropyl)disulfide (SPS), and Alcian Blue (ABPV) were used to fabricate the Cu plated layer. The additive combination was found to play an important role in the microstructural evolution of the Cu plated layer. The PC (PEG + Cl−) case produced the Cu plated layer with grains of a smaller size and random morphology, while the PCS (PEG + Cl− + SPS) and PCSA (PEG + Cl− + SPS + ABPV) cases produced the Cu plated layers with grains of a larger size and faceted morphology. Experimental results based on metallurgical examination and trace element analysis indicated that the interfacial reactions between Sn and Cu plated layers strongly depended upon the additive combination used in the Cu plating solution, and the dependence was reasonably correlated with the grain morphology of the Cu plated layer combined with the incorporation of organic impurities.