Immersion gold deposition from a chloroauric acid–choline chloride solution: Deposition kinetics and coating performances

• Developed a stable electroless Au deposition aqueous solution based on ChCl–HAuCl4.
• The solution is suitable for immersion Au deposition on Ni-P surface.
• The kinetics equation of Au deposition process was deduced.
• Ag coating increased the solderability and corrosion resistance compared with Ni-P surface.
• The activation energy of Au deposition was calculated to be 28.03 kJ·mol− 1.

A simple, green, stable, and acidic solution was developed based on choline chloride (ChCl) and chloroauric acid (HAuCl4) for immersion gold deposition onto electroless nickel substrate by galvanic displacement process. The relationships between gold (Au) deposition rate and solution parameters were investigated. The optimal conditions were determined as 1.0 g·L− 1 HAuCl4, 500 g·L− 1 ChCl, 80 °C, pH 0.5 ~ 2.5. The kinetics equation of IG deposition process was deduced and the corresponding activation energy was calculated to be 28.03 kJ·mol− 1. At the same time, the performances of the coatings were investigated. The results revealed that Au coatings prepared from chloroauric acid–choline chloride (Au(III)-ChCl) solution had excellent properties on solderability and corrosion resistance.