Novel Low Df Photosensitive Materials for Redistribution Layer

In this paper, we report low Df and negative tone type photosensitive materials with good film properties for 5G and beyond. The combination of polyimide and cyclo olefin polymer, which we have developed, achieves both excellent film properties and low Df. The less polar crosslinking groups are effective for 365 nm photosensitivity at low Df. The developed material including polyimide also showed satisfactory film properties even after biased HAST (high acceleration stress test). Finally, via patterning of 5 µm, reliable film properties and Df of 0.005 (10 GHz) were realized. This means that our material is the most promising candidate as reliable redistribution layer for next-generation semiconductor packaging.