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采用电化学阻抗谱(EIS)和扫描Kelvin探针技术(SKP)研究了热风整平无铅喷锡处理印制电路板(PCB-HASL)在模拟电解质0.1 mol/LNaHSO3以及不同pH值的0.1 mol/LNaHSO3/Na2SO3溶液中的腐蚀行为与机理,探讨了浸泡时间和pH值对其腐蚀机理转变的影响,通过OM,SEM结合EDS对PCB-HASL表面上腐蚀产物形核和扩展行为进行了观察和分析.结果表明,PCB-HASL试样在酸性NaHSO3/Na2SO3溶液体系中的腐蚀形式类似点蚀,浸泡前期腐蚀坑加速扩展,腐蚀产物主要为Sn的氧化物和硫酸盐.NaHSO3溶液能够活化PCB-HASL试样表面,且腐蚀坑形核仅发生在浸泡初期.而在中性或碱性NaHSO3/Na2SO3溶液体系中,PCB-HASL试样表面腐蚀坑形成受到抑制,电解质溶液通过氧化膜向电极界面的传输过程限制了电极反应速率.
The effects of hot air leveled PCB-HASL on the simulated electrolyte 0.1 mol / L NaHSO3 and 0.1 mol / L of different pH were studied by electrochemical impedance spectroscopy (EIS) and scanning Kelvin probe technology (SKP) / LNaHSO3 / Na2SO3 solution. The effect of immersion time and pH value on the corrosion mechanism was also discussed. The corrosion and growth behavior of PCB-HASL on the surface of PCB-HASL were observed by OM, SEM and EDS The results show that the corrosion pattern of PCB-HASL sample is similar to pitting corrosion in acidic NaHSO3 / Na2SO3 solution system, and the corrosion pits are accelerated and the corrosion products are mainly Sn oxides and sulfates in the pre-soaking.NaHSO3 solution can activate PCB- HASL sample surface and the nucleation of etch pits occurred only in the initial immersion period.In the neutral or alkaline NaHSO3 / Na2SO3 solution system, the formation of corrosion pits on the surface of PCB-HASL samples was inhibited and the electrolyte solution passed through the oxide film to the electrode interface The transport process limits the electrode reaction rate.