Three-Dimensional Printed Conformal Thick-Film Conductive Lines for High-Temperature Applications

The effective transmission of signals from high-temperature sensors in harsh environments is crucial in aerospace applications. However, the rapid fabrication of thin/thick film conductive lines (TFCLs) while avoiding damage to the substrate and minimizing disturbance remains challenging. Here, we present a strategy for the direct conformal printing of silver-palladium (AgPd) TFCLs, enabling the stable lead-out of signals from high-temperature sensors across corners without drilling the substrate, solving the problem of traditional perforated leads damaging the substrate structure. The fabricated AgPd TFCL exhibits excellent electrical performance with a low-temperature coefficient of resistance (TCR) of 197 ppm/°C (from 200 °C to 800 °C) and high long-term stability, as evidenced by a resistance drift rate (DR) of 0.71%/h (during 24 h of isothermal aging at 800 °C). Furthermore, the TFCL demonstrates outstanding scouring resistance, high bond strength, and exceptional process compatibility. As a proof of concept, a high-temperature probe was prepared, and cross-corner TFCLs enabled the nondestructive extraction of signals from a resistance temperature detector (RTD), spanning from the front to the back of the substrate. This technology establishes a foundation for signal lead-outs from sensors on specially shaped curved surfaces in extreme environments.