Thermally deposited aluminum thin films on etched PCB dielectric for application as capacitive humidity sensor

Abstract

Aluminum thin films were deposited on both sides of the etched PCB to create a capacitor. The capacitance before exposure to steam was 0.031nF. The capacitance was measured upon exposure to steam on one side and on both sides. The average capacitance for the exposure to one side is 0.100nF while the average capacitance for the exposure to both sides is 0.293nF. It was also exposed to humidity in a bell jar and the capacitance changed from 0.040nF to 0.044nF. The capacitance measurement increases once the sensor is exposed to water vapor.