Adsorption of gelatin during electrodeposition of copper and tin–copper alloys from acid sulfate electrolyte

• Copper and copper–tin deposits are investigated from acid sulfate electrolyte.
• Gelatin is used as an organic additive.
• Phenomenon of gelatin on platinum substrate modifies the electrodeposition process: the nucleation and the growth of deposits.
• The co-deposition of Cu and Sn is facilitated by gelatin.
• Gelatin is a grain refiner to copper and copper–tin coatings.

An acid Cu–Sn deposition bath was developed, and copper and copper–tin coatings were electrodeposited on polycrystalline platinum. The effect of gelatin on copper and copper–tin electrodeposition from acid sulfate solutions has been investigated by a variety of electrochemical methods (voltammetric studies and electrochemical quartz crystal microbalance) as well as by morphologic technique (scanning electron microscopy). The electrochemical results have shown that the overpotential is required when gelatin is added, indicating the presence of interaction between the additive and the coating. From the results of X-ray photoelectron spectroscopy, PM-IRRAS and cyclic voltammetry, gelatin was found to react with metal ions and platinum substrate. Adsorption of gelatin on the coating and platinum substrate is shown. Gelatin adsorption seemed to inhibit the initial nucleation of the copper and copper–tin electrodeposition, allowing homogeneous and smaller crystallites. Addition of gelatin was found to have an effect on reducing copper–tin alloys. The presence of gelatin impacts the crystal size and morphology of Cu–Sn deposits.