印刷电路板缝隙腐蚀行为研究

Crevice Corrosion Behavior of Printed Circuit Board

采用模拟印刷电路板缝隙腐蚀装置，发展阵列电极方法测试缝隙内电路板表面铜在NaCl溶液中的腐蚀电位，研究了多种因素对其缝隙腐蚀行为的影响。结果表明，缝隙宽度为20～30μm时，印刷电路板容易发生缝隙腐蚀；在浸泡初期，缝隙内铜的腐蚀电位随浸泡时间延长负移，但浸泡48h后，变化趋势较小；溶液中NaCl浓度达到1mol／L时，对促进电路板的缝隙腐蚀作用较为明显；酸性范围内，缝隙内电路板腐蚀电位随缝隙大小、浸泡时间、NaCl溶液浓度、溶液的pH值降低而负移；温度低于45℃后，缝隙内铜的腐蚀电位随温度的升高而降低。

A simulated device was designed to study the crevice corrosion behavior of printed circuit board(PCB),and array electrode technique was established to measure the corrosion potential of copper in the crevices of the PCB immersed in aqueous NaCl and investigate the effects at various factors on the crevice corrosion behavior at the copper.Thus the effects of the immersing time,dimensions of the crevice,concentration of sodium chloride,and temperature and pH value af the solution on the corrosion behavior of copper were studied.The results indicated that the crevice corrosion behavior af the PCB was dependent on various factors.Namely,the PCB was liable to crevice corrosion when the crevice gap was 20-30 μm.The corrosion potential of copper in the crevices tended to decrease at the early stage of immersion but changed little after being immersed for 48 h,and the crevice corrosion was enhanced when the concentration of NaCl reached 1 mol/L.Moreover,the corrosion potential af copper shifted negatively with decreasing crevice size,immersing time,concentration of NaCl,and pH value of the acidic solution,and it also shifted negatively with increasing temperature of the solution within a temperature range of 25-45℃.