Laser Direct Writing Lithography-Enabled Fan-Out Packaging Method for Self-Adapting LED Position Deviations

Abstract

Fan-out packaging (FOP) is promising for Mini/Micro-LED manufacturing, while chip misalignment occurs during the transferring process owing to the insufficient placement accuracy and the mismatched thermal expansion of packaging materials. This position deviation leads to interconnect misalignment between the redistribution layer (RDL) and chip electrodes, ultimately reducing packaging yield. This paper proposes a laser direct writing lithography (LDWL)-enabled FOP method to self-adapt the LED chip position deviation. The LDWL pattern is generated by machine vision according to the actual chip positions, ensuring precise interconnection between the RDL and chip electrodes. The proposed method has been successfully used to manufacture FOP LED devices, preserving excellent optoelectronic and mechanical performances, with the chip deflection tolerance of ±10° and the line width of approximately $25~\mu $ m. Our LDWL-FOP method can effectively compensate for the chip misalignment during the packaging process, showing great potential for the high-yield manufacturing of Mini/Micro-LED chips.