Thiourea, an organic additive plays a role in copper deposition and its application in the decorative electroplating and fashion accessory industries. The function of thiourea acts as a brightener agent. Thiourea (TU) in the amounts up to 60 ppm in the plating solution acts as a grain refinement on the substrate surface resulting in an improvement of the aesthetic appearance on the coating. This has been documented in the finishing literature. TU has been used in the electrorefining process to purify several metals to ensure a morphological smooth copper deposit. Regulation restrictions on lead (Pb) in Sn(Pb) solderable coatings has lead to whisker free alternatives such as Cu-Sn based using TU as a strong complexing action to electro-deposit copper together with tin.
