Assembly and integration of micro-led displays: a review of transfer methods targeting near-perfect yield

Micro-light-emitting diodes (micro-LEDs) are widely recognized for their superior brightness, efficiency, and durability, offering transformative potential for next-generation displays and emerging applications. However, the path to commercialization remains hindered by a critical barrier: achieving an extremely high production yield. Unlike conventional displays, micro-LED displays require the precise transfer of millions of individual micro-LED chips, even the slightest defects can significantly affect the overall yield. This review focuses on the technological challenges of pushing micro-LED assembly yield to extremely high thresholds of 99.99999%. We explore six key transfer methods—elastomeric transfer, roll-to-roll printing, electrostatic and electromagnetic assembly, laser transfer, microvacuum assembly, and fluidic self-assembly—and analyze their respective impacts on yield. Recent advancements in each method are discussed, with an emphasis on strategies to overcome yield challenges. By framing yield as the central metric and not as a side concern, this review aims to provide a roadmap for overcoming bottlenecks in micro-LED assembly and enabling industrial-scale deployment.