Effects of conformal coatings on the corrosion rate of PCB-based multielectrode-array-sensor

Multielectrode array sensor (MAS) for monitoring corrosion of Cu is developed using typical printed circuit board (PCB) processes. Its robustness is tested in highly corrosive HCl solutions with two different conformal coatings, namely acrylic and epoxy. It is found that the corrosion inhibiting nature of epoxy which should prolong the lifetime of epoxy-coated PCB-based MAS sensor was observed only in the initial stages of the experiment. The corrosion rate deduced from acrylic coated PCB-based MAS is more stable than the epoxy coated one. These could be attributed to the improper adhesion of epoxy onto the PCB. Therefore, although epoxy can be used as a conformal coating to prolong the lifetime of the sensor, acrylic can give more reliable corrosion rate.