Screen-Printed Thermoformed Circuits Performance and Reliability under Sustained High Temperatures for In-Mold Electronics

In-mold electronics holds the promise of lightweighting on the automotive platform for a reduced carbon footprint. The integration of the human-machine interface can be achieved on automotive surfaces with additive print processes. Screen printing holds the promise of being able to print on large surfaces while providing a high process throughput. The research objectives pursued in this paper include the evaluation of the electrical and mechanical performance of additively screen-printed thermoformed circuits when subjected to sustained high temperatures, the characterization of the long-term reliability and stability of circuits under high thermal stress, and the analysis of the failure modes and mechanisms. Circuits have been printed on polycarbonate and polyimide and performance compared with and without thermoforming. Printed line cross-sections have been measured using laser profilometry. The circuit resistivity and shear load to failure have been quantified for various sintering times and temperatures. Circuit assemblies have been fabricated using surface mount assembly of components on the substrate. Once fabricated, the assemblies have been subjected to sustained temperatures of 85°C for various periods to assess the circuit consistency, repeatability, and deviation from the theoretically expected performance.