Study of Brush-Painted Ag Nanowire Network on Flexible Invar Metal Substrate for Curved Thin Film Heater

The objective of this study was to determine the characteristics of brush-painted Ag nanowires (NW) network electrode on a SiO2 coated invar substrate for high performance curved thin film heaters (TFHs). To avoid influence of a conductive invar metal foil substrate, thin SiO2 film was deposited on an invar substrate as an insulating layer. We measured sheet resistance, optical reflectance, and surface morphology of Ag NWs/SiO2/invar as a function of the number of brush painting from one to four times. Optimized brush-painted Ag NWs network on a SiO2/invar substrate showed a low sheet resistance 38.52 Ω/square, which was acceptable for fabrication of curved TFHs. Based on a lab-made bending and fatigue tester, critical radius of the optimized Ag NWs/SiO2/invar electrode was found to be 6 mm. It demonstrated superior repeated flexibility of an Ag NW/SiO2/invar substrate. Furthermore, we demonstrated the feasibility of using a brush-painted Ag NW/SiO2/invar substrate as an electrode for curved TFHs. These curved TFHs fabricated on an Ag NW/SiO2/invar substrate showed rapid heating properties and high saturation temperature even at low applied voltage due to low resistivity of Ag NW network. This indicates that a brush-painted Ag NW/SiO2/invar substrate is a promising flexible electrode and substrate for high performance curved TFHs.