(北京科技大學(xué) 腐蝕與防護(hù)中心，北京 100083)
摘 要: 采用交流阻抗譜(EIS)和掃描Kelvin探針(SKP)技術(shù)研究4種表面工藝處理印制電路板(PCB)試樣在不同pH值稀H2SO4液滴下的腐蝕行為，通過體視學(xué)顯微鏡和掃描電鏡結(jié)合能譜對(duì)PCB上液滴擴(kuò)展和腐蝕行為進(jìn)行觀察分析。結(jié)果表明：覆銅板(PCB-Cu)在液滴作用下發(fā)生全面腐蝕；無電鍍鎳金處理電路板(PCB-ENIG)主要為微孔腐蝕，腐蝕微孔數(shù)目由液滴邊緣向液滴中心區(qū)域逐漸遞減，而化學(xué)浸銀處理電路板(PCB-ImAg)的腐蝕僅局限于液滴邊緣，兩者基底金屬均發(fā)生了不同程度的腐蝕；熱風(fēng)整平無鉛噴錫板(PCB-HASL)的腐蝕最輕微。結(jié)合EIS和SKP分析表明：稀H2SO4能夠活化液滴作用區(qū)域，增大試樣表面電位差，從而促進(jìn)試樣腐蝕；整體上，PCB-ENIG試樣的耐蝕防護(hù)性能略優(yōu)于PCB-ImAg試樣的，PCB-HASL的最優(yōu)。
關(guān)鍵字: 覆銅板；無電鍍鎳金；化學(xué)浸銀；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
