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采用扫描Kelvin探针测试技术研究了化学浸银处理(ImAg)印制电路板(PCB)在霉菌作用下的腐蚀行为,同时通过体视学显微镜、扫描电镜结合能谱分析对PCB的腐蚀和霉菌生长情况进行了观察和分析。电镜和能谱结果表明,在湿热环境下,霉菌可以在浸银处理PCB表面附着并生长繁殖,黑曲霉菌表现出更高活性,具有优先生长特性。霉菌的生长代谢作用促进浸银处理PCB的局部(微孔)腐蚀,出现漏铜现象。结合扫描Kelvin探针结果分析表明,随着时间延长,PCB表面电位整体升高,菌落区域金属作为阳极优先发生腐蚀,腐蚀产物面积逐渐扩大。虽然腐蚀反应中生成了少量带毒性的Ag+,对孢子的生长代谢有一定的抑制作用,但是这并没有阻止PCB-ImAg霉菌腐蚀的发生。浸银处理工艺不能完全抑制PCB表面霉菌的生长,不能完全满足PCB防霉菌的要求。
The corrosion behavior of chemical immersion silver (ImAg) printed circuit boards (PCBs) under the action of mold was studied by scanning Kelvin probe technique. At the same time, the corrosion and mildew of PCBs were analyzed by stereomicroscope, SEM and EDS. Growth was observed and analyzed. Electron microscopy and energy dispersive spectroscopy showed that mold could be attached and grow on the surface of PCB treated with immersion silver in a hot and humid environment. Aspergillus niger showed higher activity and preferential growth characteristics. The growth and metabolism of mold promoted the local (micropore) corrosion of the PCB treated with immersion silver, resulting in copper leakage. The results of Kelvin probe combined with scanning showed that as the time prolonged, the PCB surface potential increased overall, and the metal in the colony area preferentially corroded as the anode, and the area of the corrosion product gradually expanded. Although a small amount of Ag + was formed during the corrosion reaction, it inhibited the growth and metabolism of spores to a certain extent, but this did not prevent the corrosion of PCB-ImAg. Immersion silver treatment process can not completely inhibit the growth of PCB surface mold can not fully meet the requirements of PCB anti-mold.