Polymer-coated microelectronics: comparison of bulk, surface, and interphase conductivities

DC conductivity measurements were made at 22 °C using three test set ups. The first probed surface conductivity of specimens equilibrated with dry N₂, and with N₂ saturated with water, methanol, ethanol, or isopropanol. Experiments were performed on interdigitated comb specimens with 140-μm wide aluminum metallization lines separated by 140 μm on quartz substrates. In the second set up, comb specimens were coated with commercial siloxane polymers. Electrical measurements made on these samples reflect interphase conductivity, influenced both by bulk conductivity and by specific interactions within the polymer-substrate interphase region. The third set up measured bulk (i.e., volume) conductivity of dry polysiloxane and of polysiloxane equilibrated with water, methanol, ethanol, and isopropanol