Corrosion failure behaviours of PCBs in different marine atmospheric environments

The corrosion failure behaviours of PCB-ImAg and PCB-ImSn were investigated after exposure in the atmospheric environments of Wanning and Yantai for 12 months under a shed. The results showed that after exposure in Wanning for 12 months, the change of PCB-ImAg impedance value was that the damaged Ag layer formed a galvanic system with the Cu substrate. Meanwhile, after exposure in Yantai, the change of PCB-ImSn impedance value was mainly due to the dissolution of the Sn layer accelerated by SO 2 . The corrosion products of printed circuit boards (PCBs) were basically the same in the atmospheric environments of Wanning and Yantai. However, the SO 2 content in the Yantai environment was higher than that in Wanning, and CuSO 4 ·3Cu(OH) 2 was detected in the corrosion products from Yantai. PCBs showed different degrees of electrochemical migration (ECM) in both atmospheric environments. The atmospheric environment of Wanning was more prone to the electrochemical migration of copper because the PCB surface was more likely to form a thin liquid film. In summary, it was confirmed that the corrosion failure behaviours of PCB-ImAg and PCB-ImSn had obvious environmental dependence on ECM behaviour, which was mainly related to the content of SO 2 in different atmospheric environments and the formation of a thin liquid film.