Effect of sodium gluconate addition on anomalous codeposition of electroplated nickel-iron alloys

• Published in: Thin solid films 2024-04, Vol.794, p.140292, Article 140292
• Main Authors: Ma, Ju-Lung, Chen, Hou-Jen, Chung, Kai-Cheng, Wu, Yung-Fu, Yen, Chia-Ying, Li, Wen Jin, Lin, Hsin-Chih
• Format: Article
• Language: English
• Subjects: Anomalous codeposition; Invar; Plastic deformation; Selectivity ratio; Sodium gluconate
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2024.140292

•Environmentally friendly sodium gluconate is first used in nickel-iron plating.•Sodium gluconate exhibits stronger anomalous co-deposition than boric acid.•Sodium gluconate promotes the formation of α(BCC) and γ(FCC) mixed structures.•Grain size of nickel-iron deposit in sodium-gluconate solution is less than 10 nm. Invar nickel-iron alloy has been widely applied in the fields of electronics, sensors, communications and optics, due to its low thermal expansion coefficient, high hardness, high ductility and other characteristics according to product requirements. The application in metal stencil during the manufacturing process of active-matrix organic light-emitting diodes is mainly due to their good electrical conductivity and soft magnetic properties. In this study, sodium gluconate is used as a substitute for boric acid in the acidic electroplating of nickel-iron alloys; the concentration ratio of nickel-iron in the plating bath is 2:1. After adding sodium gluconate, the precipitation of nickel varies significantly. The iron content in the weight percentage of the deposited nickel-iron alloy is obviously larger than nickel, even up to 3 times. The whole deposition process is in the state of anomalous codeposition, and the selectivity ratio reaches 3 or more; the nickel-iron alloy deposited by adding sodium gluconate to the plating bath has a great influence on the material properties of the nickel-iron alloy plating, The nickel-iron alloy deposited at -1.4 V exhibits a hardness of approximately 3.17 GPa and a modulus of elasticity about 37.88 GPa. Notably, the resistance to plastic deformation of the alloy deposited in sodium gluconate plating solution (H3/U2=0.022) is significantly higher than that in boric acid plating solution (H3/U2=0.007). The experimental results also show that it has the best ability to resist plastic deformation.