甲酸还原镀钯及钯层耐腐蚀性能研究

Study of Palladium Layer Corrosion Resistance in Formic Acid Reduction Plating System

为了解决印制电路板(PCB)化学镀镍浸金(ENIG)表面处理工艺存在的“黑盘”现象,开发新型化学镀镍镀钯浸金(ENEPIG)工艺,在镍层与金层中间沉积钯层作为阻挡层,可有效解决“黑盘”问题。本文采用甲酸还原体系在Ni-P基底上化学镀钯,可获得不同厚度的钯层;XRD分析表明钯层以Pd(111)为主要的晶面取向;SEM表面形貌说明镀层致密性、均匀性良好;EDX测试分析说明钯层为纯钯;采用塔菲尔曲线和交流阻抗图谱研究了不同厚度镀层的耐腐蚀性,表明随着钯层厚度增加,耐腐蚀性能逐渐提高。

In order to address the issue of"black pad"phenomenon in the electroless nickle/immersion gold(ENIG)surface treatment process for printed circuit boards(PCBs),a novel electroless nickle/electroless palladium/immersion gold(ENEPIG)process has been developed.This process involves depositing a palladium layer as a barrier layer between the nickel and gold layers,which effectively resolving the"black pad"problem.In this study,varying thicknesses of pure palladium layers were obtained on the Ni-P substrate with the formic acid reduction palladium plating system.The deposited palladium layers are dense and homogeneous according the surface morphology from the scanning electron microscopy(SEM).And the palladium deposition orientated in crystal plane Pd(111)from XRD analysis.The palladium layers are pure palladium with EDX detecting.Finally,we employed Tafel plots and alternating current impedance spectroscopy to evaluate the corrosion resistance of the palladium layers.The results showed that its corrosion resistance performance improved as the thickness of the palladium layer increasing.