Sodium thiosulphate anhydrous

Catalog Number	ACEP7772987
CAS Number	7772-98-7
Structure
Molecular Formula	Na2S2O3

Case Study

Sodium Thiosulphate in Cyanide-Free Electroplating Baths for Mirror-Bright Gold Coatings

Satpathy, Bangmaya, et al. Surface and Coatings Technology 453 (2023): 129149.

This study explores the use of sodium thiosulphate in a cyanide-free electroplating bath for the deposition of mirror-bright gold (Au) coatings. The electroplating bath formulation includes chloroauric acid, sodium thiosulphate, cetyltrimethylammonium bromide (CTAB), 1,4-diazabicyclo[2.2.2]octane (DABCO), and nicotinic acid (NA), with DABCO and NA selected as effective bath additives through quantum chemical calculations.
The electrochemical behavior of the bath, analyzed using electrochemical impedance spectroscopy (EIS), shows that sodium thiosulphate plays a crucial role in stabilizing the plating process. Au coatings were deposited using pulse galvanostatic methods at various current densities (10, 50, 100, and 200 mA/cm²) and a pulse frequency of 100 Hz. The X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analyses confirmed the presence of elemental gold, while scanning electron microscopy (SEM) revealed smooth, compact microstructures in the coatings. X-ray photoelectron spectroscopy (XPS) provided insights into the atomic composition of the Au coatings.
Nano-hardness testing indicated that coating hardness decreased with increasing current density, with values of 294 ± 11.3 VHN at 10 mA/cm² and 190 ± 7.2 VHN at 200 mA/cm². These findings demonstrate that sodium thiosulphate is an essential component for achieving high-quality, mirror-bright gold coatings in a cyanide-free electroplating process.

The Role of Sodium Thiosulphate (Na₂S₂O₃) in Accelerating Electroless Gold Plating from a Sulfite-Based Electrolyte

Li, Bing, et al. Surface and Coatings Technology 302 (2016): 202-207.

This study investigates the impact of sodium thiosulphate (Na₂S₂O₃) on the acceleration of electroless gold plating from a cyanide-free sulfite-based electrolyte, with a focus on printed circuit board (PCB) manufacturing applications. It was found that adding Na₂S₂O₃ to the plating bath, within a concentration range of 0 to 8 mM, significantly increased the gold deposition rate.
X-ray fluorescence and electrochemical analysis revealed that the incorporation of Na₂S₂O₃ enhanced nickel oxidation and gold reduction, with the highest deposition rate observed at 8 mM Na₂S₂O₃, achieving approximately 0.1 μm of gold per 10 minutes.
Energy Dispersive Spectroscopy (EDS) and element linear-scanning examination identified sulfur in the deposited gold film, specifically at the interface between the nickel and gold layers. This suggests that the sulfur from Na₂S₂O₃ participates in the electroless plating process, potentially influencing the quality and consistency of the gold coating. By understanding the effect of Na₂S₂O₃, PCB manufacturers can optimize their processes to avoid sulfur-related issues, ensuring high-quality gold deposits without the use of cyanide.
These findings demonstrate that Na₂S₂O₃ is a promising additive for enhancing electroless gold plating, making it a valuable option for industries seeking cyanide-free, efficient plating solutions.

Online Inquiry

Name:

* Email:

Phone:

* Quantity:

mg g kg Service

* Services & Products Interested:

Project Description

Verification Code *

SUBMIT