Thiol계 봉공제에 의한 Au-Ni 경질 금 합금 도금층의 self-assembled monolayers(SAMs) 형성과 그 내식성 평가

초록

Gold is widely used in electronic components such as connectors and printed circuit boards (PCBs) due to its low contact resistance and excellent corrosion resistance. However, pure gold plating has low hardness and easily wears out when subjected to repeated friction. Therefore, hard gold plating with alloys such as nickel and cobalt is mainly used to improve hardness and wear resistance. However, hard gold plating has a corrosion problem from pinholes that are formed on the surface, because hydrogen gas generated during the plating process can create defects that expose the nickel layer. In this study, self-assembled monolayers (SAMs) were formed on hard gold plating layers using a single sealing agent such as 1-dodecanethiol (DDT) or 1-octadecanethiol (ODT) to seal these defects and improve corrosion resistance. Corrosion resistance was evaluated using Chronoamperometry (CA), Linear sweep voltammetry (LSV), and Electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl aqueous solution. The experimental results showed that the Au-Ni alloy sealed with ODT-based agent exhibited the lowest corrosion current density. In addition, solderability evaluation and contact resistance measurements confirmed that the ODT-based sealing treatment formed stable SAMs, effectively blocking pinhole sites and suppressing Ni diffusion.

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