Interfacial mutations in the Al-polyimide system

Abstract

Understanding the thermal stability of metal-polymer interfaces is essential for the reliability of innovative high-tech devices, including flexible electronics or satellite insulation. In this study, the interfacial stability of aluminum-polyimide (Al-PI) is investigated as a function of thermal cycling (±150°C) and thermal annealing treatments (150°C-300°C) with X-ray photoelectron spectroscopy measurements performed after peeling and cross-sectional transmission electron microscopy analysis. Small mutations in the interface chemistry and structure were detected and identified after annealing at 225°C for 140 hours, including the thickness increase of an amorphous interlayer between Al and PI of about 2 nm and a change in the failure mechanism during the peeling. Being able to trace subcritical mutations before they become fatal is essential to predict the reliability and lifetime of metal-polymer composites.