The effect of Butynediol over Nickel-Copper alloy coatings electroplated by supercritical CO2 technique

• Main Authors: Hsiang-Yun Cheng, 鄭翔云
• Other Authors: Ho-Chiao Chuang
• Format: Others
• Online Access: http://ndltd.ncl.edu.tw/handle/yg8tqa

碩士 === 國立臺北科技大學 === 機電整合研究所 === 104 === The main focus of this work is to study the co-deposition of nickel-copper alloys, with an in-depth discussion of traditional electroplating and supercritical CO2 (sc-CO2) electroplating processes. The discussion includes internal stress analysis, surface morphology, grain size, surface roughness and corrosion resistance. This work uses 1, 4-Butynediol as surfactant, and the change of surfactant content in solution is studied. Although the sc-CO2 process suffers from a decrease in efficiency because of the creation of hydrogen bubbles in solution, the supercritical emulsion can help to remove the hydrogen bubbles from the substrate surface during the electroplating process, reducing the defects generated in the thin film. When compared to the traditional electroplating process, it not only reduces internal stresses and surface roughness, but also increases corrosion resistance. The internal stresses developed inside films fabricated by supercritical electroplating have values around 20MPa less than those fabricated by traditional electroplating, when the metal films have a thickness of around 10µm. The surface roughness of films fabricated by the sc-CO2 process can be reduced by 0.02µm. Moreover, the corrosion resistance of films produced by sc-CO2 electroplating have an increase in potential by 0.05V over the traditional electroplating, and by 0.175V over pure copper. Additionally, this work utilizes scanning electron microscopy (SEM) to observe the surface micro-structures, and from the results it is seen that the surface morphology of films fabricated by the sc-CO2 electroplating process are much smoother than those produced by traditional electroplating methods. Additionally, a potentiostat was used to record and calculate the electric potential and current, plot the dynamic polarization curves, and observe the corrosion resistance of the electroplated structures for pure copper electroplating, sc-CO2 electroplating of nickel-copper alloys and traditional electroplating of nickel-copper alloys. The preferred orientation for crystal growth of the fabricated nickel-copper alloys was observed by X-ray diffraction (XRD) analysis, and no matter the process used, the preferred orientation was always the (111) direction; the 1, 4-butyneidol content in solution also did not affect the preferred orientation. Finally, the effect of the different fabrication processes over the size of grains is calculated, and it is evident that sc-CO2 electroplating achieved the highest degree of grain refinement.