Corrosion assessment of passivation film generated on solder surface in artificial sweat solution

As the electric joint, the reliability of solder alloy is very important for the circuit card. Since the corrosion might lead to the failure of solder, various characterization methods have been used to assess the corrosion property of Sn-0.7Cu solder alloy in artificial sweat such as the potentiodynamic (PD) polarization, the potentiostatic (PS) polarization, the electrochemical impedance spectroscopy (EIS) and Motty-Schottky (MS) measurement. The EIS results showed that the passivation film owns better barrier properties in alkaline artificial sweat solution. The analysis of electrical equivalent circuit suggested that the passivation film resistance in alkaline solution is two orders of magnitude higher than that in acid solution, which were also supported by MS measurement. The better barrier properties of intact passivation surface contributed to corrosion resistance in alkaline artificial sweat solution. After a typical PD polarization process, the scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) has been employed to characterize surface morphology and chemical composition of passivation surfaces. This work can provide some suggestions for the personalized design of wearable devices by considering the sweat corrosion effect.