Novel Photo Imageable Film for RDL Application

This paper presents the development of novel photosensitive films designed for use in the redistribution layers (RDL) of advanced semiconductor packages. Traditional photosensitive polyimides, being liquid-based, suffer from challenges such as inadequate surface planarization and distortion caused by high curing temperatures. The newly developed films aim to address these issues effectively. Key advancements include enhanced surface flatness achieved through vacuum lamination, eliminating the need for additional processes like chemical-mechanical polishing (CMP). These films exhibit reduced cure shrinkage and lower curing temperatures compared to conventional polyimides, significantly minimizing package distortion. With a low dielectric loss tangent of approximately 0.005 at 10 GHz, they can be developed using polar organic solvents. Moreover, the films facilitate microvia formation via photo-imaging processes, playing a critical role in RDL applications. These innovations enable the new photoimageable films to deliver superior performance and increased utility in semiconductor packaging, particularly suited for high-speed communication RDLs. The material is a dry film type that forms flat insulating layers over various circuit patterns without requiring additional processing, while also offering exceptional dielectric properties unattainable with traditional RDL materials.