Performance and Reliability of In-Mold Direct-Write Signal Processing Circuits in Sustained High-Temperature Operation

Abstract

Abstract As additive in-mold technologies gain traction in the automotive sector, there is a growing need for long-term reliability data under harsh conditions and acceleration factors to predict the technology’s lifespan. This paper aims to investigate how the performance and reliability of a system or device evolve over time under continuous, elevated temperature conditions. The research methodology involves thorough investigations into materials, manufacturing processes, and testing procedures to assess the reliability of in-mold flexible electronics. To simulate the harsh conditions typically encountered by automotive components, printed thermoformed samples are subjected to prolonged exposure to high temperatures in this study. The nScrypt direct write platform is utilized for printing connection materials and conductive traces. Stretchable electrically conductive adhesive (ECA) is the connecting medium, while in-mold capable silver ink is utilized for the conductive traces. Thermoformable polycarbonate sheets are employed as substrate materials, with Formech-508FS utilized for thermoforming purposes. To evaluate the performance of the additively printed thermoformed circuit, an impedance analyzer is employed. A functional circuit schematic is constructed and tested using OrCAD PSpice to simulate the application. The actual output of the printed thermoformed circuit before exposure to high thermal conditions and during High-Temperature Operating Life (HTOL) testing is compared with the simulated performance of the circuit.