Mechanical and Electrical Properties of Au-Ni-C Alloy Films Produced by Pulsed Current Electrodeposition

Abstract

Au-Ni-C alloys films electrodeposited by a pulsed current method were investigated to assess the crystalline structure, sheet resistance, and wear resistance, for use as an electronic contact material. In particular, we have analyzed the effects of citric acid concentration and pulse off-time on the mechanical and electrical properties of the electrodeposited Au-Ni-C alloy films. The electrodeposition bath used in this study was composed of K[Au(CN) 2 ] and NiSO 4 · 6H 2 O as precursors, and citric acid as the complexing agent. The film microstructure and composition were controlled by adjusting the interval of pulse off-time and the concentration of citric acid. With the prolongation of the pulse off-time interval, XRD results indicated that the amorphous structure with high Ni and C contents was transformed into a nanocrystalline structure, followed by the formation of crystals with small Ni and C contents. The amorphous and nanocrystalline films showed a high Knoop hardness of ca. 500 kg mm −2 , while that of the crystalline films was found to be 300 kg mm −2 . The wear resistance of the film electrodeposited by the pulsed current method was remarkably good compared to that of the direct-current electrodeposition films, even though both films exhibited essentially identical microstructure and composition. The wear property was considered to be relevant to the restoration of the surface flatness of the film by the galvanic displacement deposition of Au during the pulse off time.

High-Strength Electroplated Au–Cu Alloys as Micro-Components in MEMS Devices

“…9 To overcome these predicaments, alloying the electroplated Au is suggested to be the solution and allows further strengthening by the solid solution strengthening mechanism. [10][11][12] On the other hand, Vickers micro-hardness measurement is widely used to characterize mechanical properties of the electroplated metallic materials. 13,14 However, the obtained results are often affected by the substrate, which may not represent the real strength of the electroplated materials.…”

Development and characterization of magnetron sputtered self-lubricating Au-Ni/a-C nano-composite coating on CuCrZr alloy substrate

“…In high-reliability systems, high-performance Au coatings are required, and alloying Au with a small amount of other metal elements, such as Co and Ni, can generate harder Au coatings which exhibit distinct performance improvement [1,[6][7][8]. Hard Au coatings are generally obtained from acidic-cyanide baths in which nickel or cobalt salts are added as the hardening/brightening agents [3,4,[9][10][11][12]. Although Au-Ni and Au-Co alloy coatings exhibit a higher wear resistance compared to soft Au, adding solid lubricant materials into alloy coatings is beneficial for decreasing the wear rate by minimizing the adhesive wear.…”

Pulse Electroplating of Gold-Nickel Alloys: Morphological and Aesthetic Improvement Compared to DC

“…[7][8][9] As previously introduced, Au materials fabricated by electroplating have been commonly used as contact materials for high reliability circuit boards, electrical connectors, relays, and micro-and nano-scale electronic components for many decades because of their high electrical conductivity, chemical stability, corrosion resistance, and ductility. [10][11][12] Electrodeposition of gold or its alloys is not only used in the electronics industry due to its conductive and anti-corrosive properties, but also as a final layer due to its aesthetic properties, 13,14 good mechanical properties and excellent biocompatibility, 9 in fact only 7% of the gold mined each year is used for medical, industrial and technological purposes while the remaining 93% is used in the jewelry industry and banking (e.g. in the production of bars or coins).…”