High-Planarity, Ultra-Low-Temperature-Curable Photosensitive Polyimide for Heterogeneous Integration

In this study, we developed a novel negative tone photosensitive polyimide with ultra-low temperature (<200°C) curability and high planarity to reduce undulation of the substrate including a 10 μm thickness line pattern and Cu wire. In addition, this photosensitive polyimide achieved 5 μm via holes at 5 μm thickness on the Cu substrate, low coefficient of thermal expansion (50 ppm/K) and high Tg (230°C) when cured at 170°C.