Surface Morphology Study: Effect of Electrolyte pH on the Electrodeposited Sn-Ag-Cu (SAC) Solder Alloy

Abstract

pH control is significant in electrodeposition because they affect the characteristics of electrolyte and the deposit. This paper mainly analyses the processing conditions of electrolyte pH value on the electrodeposited SAC. Sn2+ ions will be obtained from the tin methane sulphonate acid while the Cu2+ and Ag+ ions will be obtained from their respective sulfate salts. Ammonium acetate helps in raising the pH of the bath. The FESEM analysis was carried out to examine the morphology of the electrodeposited nanocomposites. A variety of morphological patterns for the electrodeposits with different electrolyte pH is obtained. At low pH (2) electrolyte value, the electrodeposits show a very poor quality with rough surface. With increasing pH value (2.5), the averaged grain sizes decreased. The surfaces of the films electrodeposited at this pH value are generally quite smooth, uniform and compact. Later increment of pH values (3~4) has lead to the formation of porous and non-uniform electrodeposits. From the study, it is possible to observe that, even with the same composition, the deposits have different morphologies under different controlled parameter.