Fabrication of transparent antennas on thin glass substrates using conventional fabrication methods is discussed. Two transparent conductors (a) indium tin oxide (ITO) and (b) copper meshes were used in fabrication. Two antennas operating at 2.4 GHz and 5.8 GHz were designed, simulated, and fabricated on flexible glass using ITO as the conductor. The test results indicate radiation efficiencies of 92% and 49% for 2.4 GHz and 5.8 GHz antennas, respectively. A copper mesh antenna was designed, simulated, and fabricated for automotive applications operating at 4G LTE (fourth generation broadband cellular network based on the long-term evolution communication standard) radio bands from 690 MHz and up to 2200 MHz. An etched copper mesh antenna with 10–100 μm line-period combination showed ∼80% transmission in visible range and 0.2 Ω/sq sheet resistance. A semi-additively fabricated copper mesh antenna with 10–100 μm line-period combination showed ∼75% transmission in visible range and 0.1 Ω/sq sheet resistance. On-vehicle radio frequency (RF) testing confirmed that these antennas performed well, with etched and semi-additive transparent mesh antennas having close performance. The fabrication process developed on wafer level was optimized to be fully compatible with roll-to-roll (R2R) manufacturing.

Flexible glass has many applications including photovoltaics, organic light-emitting device (OLED) lighting, and displays. Its ability to be processed in a roll-to-roll facility enables high-throughput continuous manufacturing compared to conventional glass processing. For photovoltaic, OLED lighting, and display applications, transparent conductors are required with minimal optical reflection losses. Here, we demonstrate an anti-reflective coating (ARC) that incorporates a useful transparent conductor that is realizable on flexible substrates. This reduces the average reflectivity to less than 6% over the visible band from normal incidence to incident angles up to 60°. This ARC is designed by the average uniform algorithm method. The coating materials consist of a multilayer stack of an electrically functional conductive indium tin oxide with conductivity 2.95×105  Siemens/m (31 Ω/□), and AlSiO2. The coatings showed modest changes in reflectivity and no delamination after 10,000 bending cycles. This demonstrates that effective conductive layers can be integrated into ARCs and can be realized on flexible glass substrates with proper design and process control.

There has been an increasing need for antennas in automotive applications, for communications applications, such as cellular, satellite radio, and the burgeoning fields of selfdriving/ networked vehicles and 5G. These applications demand alternatives to traditional vehicle antennas, including transparent antennas able to be unobtrusively mounted to vehicle windows. Flexible glass provides a high quality transparent and flexible substrate for the fabrication of these antennas, and that is amenable to low cost roll-to-roll manufacturing. Sheet scale prototype transparent antennas were fabricated in copper using etch back and semi-additive processes, with conventional processes and facilities, and using materials and processes amenable to roll-to-roll fabrication. This shows that flexible glass could be used in existing lines and facilities with little modification, in addition to roll-to-roll processing. Fabricated antennas were tested on-vehicle and show good performance, with similar gain figures for baseline solid antennas, etched transparent antennas, and semi-additive transparent antennas

Efficient antennas were achieved at 2.4 GHz and 5.8 GHz in which a transparent conductor, ITO, was deposited on only one side of the glass through sputtering. Antenna structures including grid, loop, and split ring monopoles were also designed and tested. An ITO layer of 650 nm was needed to consistently maintain a sheet resistance of 10 ohms/square or less to reduce antenna losses. A 100 nm aluminum doped silicon dioxide layer was deposited to buffer the ITO from the flexible glass to ensure high conductivity, and photolithography was used to define the antennas followed by an annealing process to improve the ITO conductivity and transparency. A packaging technique using 3D printed frames, Corning® GPPO connectors, and conducting epoxies yielded good antenna performance in terms of radiation efficiency and mismatch loss. Good agreement between simulations and measurements for packaged devices was obtained. Examples of antenna packaging, measurement results, and performance are presented.

Flexible glass is one of the most promising innovations in the 21st century. Its applications in roll-to-roll (R2R) based manufacturing can yield low cost, conformable, and transparent electronics. In this work, we introduce electronic interposer substrates consisting of multiple metal-insulator layers of subtractively processed single micron metal circuit lines as well as high performance IGZO thin film transistors fabricated on Corning® Willow® Glass. All processes are compatible with R2R patterning and fabrication.