Characterization of Electroless Nickel–Boron Deposit from Optimized Stabilizer-Free Bath

Abstract

Conventional electroless nickel–boron deposits are produced using solutions that contain lead or thallium, which must be eliminated due to their toxicity. In this research, electroless nickel–boron deposits were produced in a stabilizer-free bath that does not include any toxic heavy metal. During processing, the plating rate increased from 10 to 14.5 µm/h by decreasing the concentration of the reducing agent, leading to increased bath stability. The thickness, composition, roughness, morphology, hardness, wear, and corrosion resistance of the deposits were characterized. The new deposit presents an excellent hardness of 933 ± 56 hv50, 866 ± 30 hk50, and 12 GPa from the instrumented indentation test (IIT), respectively, which are similar to that of hexavalent hard chromium coating. Moreover, by using both potentiodynamic polarization and salt spray tests it was shown that the coating presents higher corrosion resistance as compared to standard nickel-boron coatings. The new deposit exhibits properties close to those of the conventional electroless nickel–boron deposits. Therefore, it could replace them in any industrial applications.

A critical review of copper electroless deposition on glass substrates for microsystems packaging applications

“…The substrate is a catalytic surface on which metal is to be deposited. This reaction can be divided into two sections according to mixed potential theory [42,73]: cathodic partial reactions and anodic partial reactions. Cathodic partial reaction (Equation (2)) and anodic partial reaction (Equation (3)) are used to reduce metal ions and oxidize the reducing agent.…”

“…An electroless deposition bath consists of metal ion sources, reducing agents, complexing agents, and additives. Reducing agents are the solution's driving force for reducing metal ions [64][65][66][67][68][69][70][71][72][73][74]. Electroless deposition is initiated once catalyst particles are available on the substrate surface [67].…”

“…Researchers are also working on the electroless deposition of nickel–boron. Yunacti [73] used a stabilizer-free electroless bath that did not contain toxic heavy metals. The properties of deposits were close to the lead-stabilized bath.…”

YSZ/Ni double‐shell powder via surface electroless deposition tuned by an active kinetic model

“…Researchers found that the deposition rate increased and decreased with increasing concentrations of nickel sulfate, sodium hypophosphite, pH, and bath temperature 23–25 . However, Yunacti et al 26 . found that during processing, the plating rate increased with decreasing reducing agent concentration.…”

“…Researchers found that the deposition rate increased and decreased with increasing concentrations of nickel sulfate, sodium hypophosphite, pH, and bath temperature. [23][24][25] However, Yunacti et al 26 found that during processing, the plating rate increased with decreasing reducing agent concentration. To understand the intrinsic relationship between the deposition rate during process and the duration, researches [27][28][29] showed that electroless plating consists of different stages with various deposition rates.…”