Alkoxylated beta-Naphthol as an Additive for Tin Plating from Chloride and Methane Sulfonic Acid Electrolytes

作者：Zajkoska Simona P^*; Mulone Antonio; Hansal Wolfgang E G; Klement Uta; Mann Rudolf; Kautek Wolfgang

来源：Coatings, 2018, 8(2): 79.

DOI：10.3390/coatings8020079

• tin electrodeposition
• alkoxylated beta-naphthol
• chloride
• methane sulfonic acid
• exchange current density
• grain size

beta-naphthol was one of the first additives introduced for smooth and homogeneous tin electrodeposition. Although it can be oxidized under the plating conditions, forming either 1,2-napthoquinone or polymeric materials based on naphthioxides, it is still in use. In this work, an investigation of its more stable form, alkoxylated beta-naphthol (ABN), on tin plating is undertaken. For this purpose, chloride based (pH similar to 5) and methane sulfonic acid (MSA, pH similar to 0.5) electrolytes, including ABN, were prepared. Reaction kinetics were studied by polarization, Tafel measurements, and cyclic voltammetry. Tin electrodeposits were obtained on flat brass substrates. Surface morphology and preferred crystal orientation were studied by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). In both studied electrolytes ABN acts as an inhibitor but in the case of the chloride electrolyte it is more pronounced. In the MSA electrolyte this effect was overlaid by the presence of tin-citrate complexes. In the chloride-based electrolyte, ABN has a grain refining effect, while in the MSA electrolyte an increase of ABN concentration leads to a slight enlargement of the average grain size. X-ray analysis shows a constant decrease of the (101) intensity with increasing concentration of ABN for the sample deposited from both baths.

• 出版日期2018-2