Novel low-temperature curable photosensitive polyimides with stable storage

In this work, varieties of thermal base generators with nitrogen heterocyclic bases as curing catalysts were synthesized and further blended with photo-crosslinking agents, and photoinitiators to achieve the research goal of the low-temperature curable negative photosensitive polyimide (n-LTPI) photoresist. Due to the addition of thermal base generators, the curing temperature was reduced to 200 °C. Adding 2% 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) pyromellitic acid salt to the photoresist can completely iminate at 200 °C. Through field-emission scanning electron microscope analysis, the film produced high-quality photo-patterns with line and via resolution of 2–5 μm at 5–6 μm film thickness. Compared with existing technologies, our article not only achieves low-temperature curing of photoresists but also improved storage stability, which has great practical value in the field of advanced semiconductor packaging.