Corrosion Behavior of Printed Circuit Boards in Tropical Marine Atmosphere

Abstract

Outdoor exposure experiments of PCB-Cu, PCB-ImAg and PCB-ENIG were conducted in a tropical marine atmosphere under the synergistic effect of multiple factors, and the corresponding corrosion behavior of the PCBs was investigated by SEM, EDS and EIS. The results indicated that PCB-ImAg had strong resistance to Cl, and the surface was covered only by several spores, without obvious corrosion products, and it had excellent corrosion resistance. PCB-ENIG was covered with dense corrosion products, and it had poor biocompatibility and was detrimental to the growth of molds. PCBCu was significantly corroded, and an obvious shedding of surface corrosion products was observed, with the corrosion rate increasing constantly during the exposure periods. All the corrosion occurred at the active sites where dust particles, salt particles and mold spores were scattered. The probable corrosion mechanism of PCBs inferred that defects in the coatings of PCB-ImAg and PCB-ENIG acted as pathways for the corrosive electrolyte liquid, and the copper substrate was corroded, and localized corrosion cells accelerated the corrosion. Additionally, long-term exposure led to the formation of a double-layer structure in PCB-Cu, with an inner oxide film and an outer layer of loose corrosion products, consequently providing a weak protection effect.