Abstract: Positive tone photosensitive polyimide
having low-temperature curability and extremely good Cu migration was developed.
If the patterning of PDL on OLED panels can be achieved using a negative-tone black photoresist  containing black pigment instead of the positive-tone photoresist based on photosensitive polyimide, the photolithographic process of patterning BM on top of the PDL pattern would be omitted.
The use of negative-tone black photoresist, instead of positive-tone photoresist based on photosensitive polyimide could remove both the BM patterning and the 1/4[lambda] polarizing film by reducing the reflection of ambient light from the OLED panel.
Further, a high thermal stability of the binder polymer that corresponds to the photosensitive polyimide in the positive-tone photoresist is required.
Over the past decade and a half, there has been substantial interest in photosensitive polyimides (PSPIs) (1).
Because the intrinsically photosensitive polyimides are already in their fully converted state, and because they gel upon exposure to ultraviolet light, they show strong potential as high performance materials that can be cured rapidly and at low temperatures.
The chemical mechanism of UV crosslinking in inherently photosensitive polyimides has been studied (16, 20-22).