(北京科技大学 腐蚀与防护中心，北京 100083)
摘 要: 采用交流阻抗谱(EIS)和扫描Kelvin探针(SKP)技术研究4种表面工艺处理印制电路板(PCB)试样在不同pH值稀H2SO4液滴下的腐蚀行为，通过体视学显微镜和扫描电镜结合能谱对PCB上液滴扩展和腐蚀行为进行观察分析。结果表明：覆铜板(PCB-Cu)在液滴作用下发生全面腐蚀；无电镀镍金处理电路板(PCB-ENIG)主要为微孔腐蚀，腐蚀微孔数目由液滴边缘向液滴中心区域逐渐递减，而化学浸银处理电路板(PCB-ImAg)的腐蚀仅局限于液滴边缘，两者基底金属均发生了不同程度的腐蚀；热风整平无铅喷锡板(PCB-HASL)的腐蚀最轻微。结合EIS和SKP分析表明：稀H2SO4能够活化液滴作用区域，增大试样表面电位差，从而促进试样腐蚀；整体上，PCB-ENIG试样的耐蚀防护性能略优于PCB-ImAg试样的，PCB-HASL的最优。
关键字: 覆铜板；无电镀镍金；化学浸银；稀H2SO4
（Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083, China）
Abstract:The electrochemical impedance spectroscopy (EIS) and scanning Kelvin probe (SKP) testing techniques were used to study the corrosion behavior of four kinds of printed circuit boards (PCB) under dilute H2SO4 droplets with different pH values. Meanwhile, the corrosion morphology was observed and analyzed. The results show that general corrosion occurs on the printed circuit board PCB (PCB-Cu) surface under the droplet. The corrosion behavior of electroless nickel immersion gold finishing PCB (PCB-ENIG) is mainly in form of microporous corrosion, and the corroded micropores develop from the edge of droplet to the center, while the corrosion regions of immersion silver finishing PCB (PCB-ImAg) are confined at the edge region of droplet, the substrate metals for PCB-ENIG and PCB-ImAg are both corroded to some extent. Among four PCB materials, the hot air solder leveling PCB (PCB-HASL) corrodes the most mildly. EIS and SKP results show that the dilute sulfuric acid droplets can activate the sample surface and form a large potential difference on the whole droplet region, contributing to the further corrosion process. Overall, the corrosion resistance and protection performance of PCB-ENIG is better than that of PCB-ImAg, while PCB-HASL is the best without any corrosion occurring on the substrate.
Key words: printed circuit board; electroless nickel immersion gold; immersion silver; dilute H2SO4
